Addressability in particle detection

ABSTRACT

A method of determining at least one point of entry of smoke into a smoke detection system, the system having a sampling pipe network including at least one sampling pipe and a plurality of sampling inlets through which an air sample can enter the at least one sampling pipe of the smoke detection system for analysis by a particle detector, said method including: determining a volume of sample air that has passed through at least part of the smoke detection system since a predetermined event or a value corresponding to said volume; and determining through which sampling inlet of the plurality of sampling inlets the smoke entered the smoke detection system based, at least in part, on the determined volume or value. Systems for implementing such a method and related methods are also described.

RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.14/433,201, filed 2 Apr. 2015, which claims the benefit of Australianprovisional patent applications: 2012904516, filed 16 Oct. 2012;2012904854, filed 2 Nov. 2012; 2013902076, filed 7 Jun. 2013; and2013902570 filed 11 Jul. 2013; and Australian complete patentapplication 2013200353, filed 21 Jan. 2013, each of which areincorporated herein by reference for all purposes.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to particle detection. For illustrativepurposes only, the preferred embodiment of the present invention will bedescribed in relation to a smoke detection system, but the inventionshould not be considered to be limited to that exemplary use.

2. Discussion of the Related Art

Air sampling or aspirated smoke detection systems operate by drawing airsamples through a sampling network, to a central high sensitivityparticle detector. The sampling network typically includes one or moresample pipes with a number of air sample inlets in the form of samplingholes or sampling points located along the length of the pipe(s). Insuch an arrangement, a single detector may be fed with air originatingfrom many distinct geographical locations at which the air sample inletsare located. Thus a single such detector can monitor for the presence ofsmoke at many distinct locations simultaneously.

One recognised difficulty with air sampling systems as described aboveis that they do not identify through which air inlet smoke enters thesystem. If the air inlet is known, the geographical location of thesource of the smoke may be inferred. This allows investigation of thelikely site of the fire including allowing a person to be directed tothe location of the smoke, so that they may investigate and possiblyintervene and prevent further growth of the fire, or shut down equipmentin the area. Alternatively, an appropriate fire suppression system maybe deployed in a localised way, limiting damage caused by the system, aswell as expense.

There have been attempts to provide air sampling particle detectionsystems capable of determining the geographical location at which smokeis detected, for example Jax, ‘Method and Device for locatingaccumulations of pollutants’, U.S. Pat. No. 5,708,218 and HekatronVertriebs GmbH, ‘Verfahren and Vorrichtung zur Erkennung eines Brandes’,EP 1811478.

Each of these systems measures the elapsed time between two instants atwhich measurements are made to infer where along sampling pipe (i.e.through which sample inlet) the detected smoke entered the system.However, this inferential process is often unreliable.

The Jax system measures the elapsed time between detection of a firstsmoke level, and a second smoke level. The time between detection of afirst, lower level of smoke, and a second, higher level of smokeindicates the distance along the collection line at which smoke enteredthe system. However, this process may be inaccurate. For example,systems employing this approach rely upon the actual level of smokedetected at the first point of entry remaining approximately constantfor the period of time beginning from the point at which smoke is firstdetected until the contribution from the second point of entry can bereliably detected. More specifically, an increase in smoke level, suchas that caused by a fire of growing size, may result in an inaccurateestimate of the geographical location from which air has been drawn.

In Hekatron, a first air-sampling detection unit detects the presence ofsmoke. Responsive to detection of smoke, a second air-sampling detectionunit is engaged, the air sampling unit drawing air along the pipenetwork. The time elapsed between initial detection by the firstair-sampling unit and detection by the second air-sampling unit ismeasured. Ideally, the time elapsed indicates the location from whichsmoke filled air has been drawn. To ensure accuracy, such a systemrequires the aspiration system to operate in a highly consistent manner,each time it is operated. However, this is difficult to achieve asvarious features influence the operation of the fall, e.g. degradationof the aspiration system over time and variations in operational andenvironmental conditions e.g. air density, or the constriction ofsampling points by dirt over time, will change the airflowcharacteristics within the system, and make the inference of the smokeaddress based on elapsed time potentially unreliable.

In some schemes, airflow may be temporarily reversed, introducing cleanair to the sampling network, before redrawing air for detection. Theidea in such schemes is to flush substantially all smoke particles fromthe system, before redrawing air through the sampling network andmeasuring the delay before detecting smoke. In theory, a longer delayindicates that the particles entered the sampling network at a pointfarther from the detector. However, these schemes suffer a drawback inthat during the phase that clean air is introduced to the samplingnetwork, smoke particles within the monitored environment may bedisplaced in the area surrounding the air inlets, since clean air isbeing expelled from the inlets. When air is subsequently drawn throughthe system, there may be an additional delay before smoke particles areonce again drawn into the inlet.

It is therefore an object of the present invention to provide a particledetection system that addresses at least some of the aforementioneddisadvantages. An alternative object of the invention is to provide thepublic with a useful choice over known products.

Reference to any prior art in the specification is not, and should notbe taken as, an acknowledgment or any form of suggestion that this priorart forms part of the common general knowledge in Australia or any otherjurisdiction or that this prior art could reasonably be expected to beascertained, understood and regarded as relevant by a person skilled inthe art.

SUMMARY OF THE INVENTION

In a first aspect of the present invention there is provided a method ofdetermining at least one point of entry of smoke into a smoke detectionsystem, the system having a sampling pipe network including at least onesampling pipe and a plurality of sampling inlets through which an airsample can enter the at least one sampling pipe of the smoke detectionsystem for analysis by a particle detector. The method includes:determining a volume of sample air that has passed through at least partof the smoke detection system since a predetermined event or a valuecorresponding to said volume; and determining through which samplinginlet of the plurality of sampling inlets the smoke entered the smokedetection system based, at least in part, on the determined volume orvalue.

The predetermined event could be, for example, a smoke detection event;or a change in an air sample flow characteristic in the smoke detectionsystem.

In some embodiments the method includes continuously determining a flowrate of the air sample passing through at least part of smoke detectionsystem. Alternatively the method includes commencing determination ofthe volume of sample air or a related value upon the occurrence of thepredetermined event.

The volume of the air sample that has passed through at least part ofsmoke detection network or a related value can be determined byaccumulating a flow rate measurement over time. The rate of flowmeasurement is preferably a volumetric flow rate measurement. Mostpreferably the he flow rate measurement is determined using anultrasonic flow sensor.

The step of determining a volume of sample air that has passed throughat least part of the smoke detection system since a predetermined eventor a value corresponding to said volume, can include determining any oneof more of: a mass; a length; a pressure; a temperature, a secondvolume; or an accumulated count of volume-related events, or otherparameter that that relates to a volume of sample air that has passedthrough at least part of the smoke detection system since thepredetermined event.

The method can include collecting all or a proportion of the sample airthat has passed through at least part of the smoke detection systemsince the predetermined event.

The method can further include changing an air sample flowcharacteristic in response to a first smoke detection event. Forexample, changing an air sample flow characteristic in the smokedetection system can include one or more of the following:

-   -   opening a valve;    -   closing a valve;    -   changing a direction of an air sample flow in at least part of        the smoke detection system;    -   changing a rate of air sample flow in at least part of the smoke        detection system;    -   starting an aspiration system; and    -   stopping an aspiration system.

In a second aspect of the present invention, there is provided anapparatus for determining at least one point of entry of smoke into asmoke detection system of the type having a particle detector in fluidcommunication with an air sampling network, the air sampling networkhaving at least one sampling pipe and a plurality of sampling inletsthrough which an air sample can enter the at least one sampling pipe ofthe smoke detection system for analysis by the particle detector, and anaspirator for drawing the air sample through the air sampling network tothe detector. The apparatus includes: means for determining a volume ofsample air that has passed through at least part of the smoke detectionsystem since a predetermined event or a value corresponding to saidvolume; and means for identifying at least one point of entry ofparticles into the sampling network based on the detected volume orvalue.

The apparatus preferably identifies one or more of said points of entryby reference to one or more corresponding sampling inlets through whichsmoke determined to have entered the system.

The means for determining a volume of sample that has passed through atleast part of the particle detection system, or value related to saidvolume, preferably includes a flow sensor. Most preferably the flowsensor comprises an ultrasonic flow sensor.

The apparatus is preferably configured to perform a method in accordancewith the first aspect of the present invention.

In a third aspect of the present invention, there is provided a smokedetector including a particle detection chamber to detect particles inan air sample, an inlet to receive an air sample from an air samplingnetwork, said the sampling network having at least one sampling pipe anda plurality of sampling inlets through which a sample can enter the atleast one sampling pipe for analysis by the particle detection chamber,and an aspirator for drawing the sample through the air sampling networkto the detector, the detector further including a processor configuredto: identify at least one point of entry of smoke into the samplingnetwork based, at least in part, on a volume of sample air that haspassed through at least part of the smoke detector or sampling networksince a predetermined event, or a value corresponding to said volume.

The smoke detector can include a flow sensor, e.g. an ultrasonic flowsensor, configured to detect rate of flow of sample air passing throughat least a part of the smoke detector.

The processor is preferably configured to cause the smoke detector toperform a method in accordance with the first aspect of the presentinvention.

Also disclosed herein is a method of determining the point of entry ofparticles into a particle detection system, said particle detectionsystem including a particle detector and a sampling network in fluidcommunication with the particle detector, the sampling network includinga plurality of inlets through which a fluid is drawn, the particledetection system further including means for drawing fluid through thesampling network to the detector. The method includes: comparing a firstparticle detection profile to a second particle detection profile;determining an offset between the particle detection profiles at whichthe profiles match to a predetermined degree; and, determining alocation of entry of particles into the detection system on the basis ofthat offset.

In some embodiments, the offset is a time offset. In other embodiments,the offset is a volume offset.

In some embodiments, the comparison involves calculation of across-correlation between particle detection profiles.

In some embodiments, a maximum value of the calculated cross correlationis determined, and an offset between particle detection profilescorresponding to the maximum value is determined.

In some embodiments, the calculated cross correlation function isdetermined and compared to a predetermined value.

Preferably, the fluid is air, and the means for drawing fluid throughthe sampling network to the detector is an aspirator.

One embodiment includes determining that at least a first predeterminedparticle detection criteria has been met on the basis of a firstparticle detection profile being a comparison of the first and secondparticle detection particles.

The method can include continuously storing a first and/or secondparticle detection profile. Alternatively one of the profiles may bestored only after at least one predetermined criteria has beenfulfilled.

The method can include changing an air flow characteristic in at leastpart of the particle detection system prior to beginning a comparison ofthe first and second particle detection profiles.

In one form the step of changing an air flow characteristic in theparticle detection system includes one or more of the following:

-   -   opening a valve;    -   closing a valve;    -   changing a direction of an air flow in at least part of the        particle detection system;    -   changing a rate of air flow in at least part of the particle        detection system;    -   starting an aspiration system; and    -   stopping an aspiration system.

Further disclosed herein is an apparatus for determining the point ofentry of particles into a particle detection system of the type having aparticle detector in fluid communication with an air sampling network,the air sampling network having a plurality of inlets through which airmay enter the air sampling network, and an aspirator for drawing airthrough the air sampling network to the detector, the apparatusincluding means for determining a volume of air passing through at leasta part of the particle detection system, said apparatus including: meansfor receiving a signal representative of the volume of air passingthrough at least a part of the particle detection system; means fordetermining a location in the air sampling network at which air carryingparticles entered the network on the basis of the determined volume.

Also disclosed herein is a device for determining the point of entry ofparticles into a particle detection system through one or more of aplurality of air inlets. The device includes means for determining avolume of air flowing through at least part of the particle detectionsystem and means for determining a point of entry of the particles basedupon the measured volume.

Preferably, the apparatus for determining the point of entry ofparticles into the particle detection system identifies the source ofparticles by reference to at least one inlet through which particles arelikely to have entered.

Further preferably, the apparatus for determining the point of entry ofparticles into the detection system identifies the source of particlesby providing an indication of the distance of along the sampling networkat which particles entered the air sampling network.

Further disclosed herein is a method of determining the point of entryof particles into a particle detection system having a sampling pipenetwork with a plurality of sampling points through which particles canenter the particle detection system. The method includes, determiningthe volume of air passing through at least part of particle detectionsystem and determining through which sampling hole of the plurality ofsampling points the particles entered the particle detection system.

The method can include, detecting a first particle detection event and asecond particle detection event, and measuring the volume of air passingthrough at least part of particle detection network between the particledetection events.

The method can include continuously measuring the volume of air passingthrough at least part of particle detection network. Alternatively themethod can include activating the volume measurement upon the occurrenceof a predetermined condition.

The volume of air passing through at least part of particle detectionnetwork is preferably measured by summing a rate of flow measurementover time. Preferably the rate of flow measurement is a volumetric flowrate measurement. Most preferably it is determined using an ultrasonicflow sensor.

Further disclosed herein is a particle detection system including aparticle detector, a sampling network in fluid communication with theparticle detector, and means for drawing fluid through the samplingnetwork to the detector. The sampling network includes a plurality ofinlets, the inlets being arranged into a plurality of location groups.Each location group has an address defined by the presence or absence ofan inlet connected to each of a plurality of sampling pipes. Theparticle detector is configured to draw air along each sampling pipe andin the event that smoke is detected, determine the address of thelocation group through which particles entered the detector based uponboth the presence and absence of particles in each of the samplingpipes.

Also disclosed herein is a method of determining a single point of entryof particles into a particle detection system. The particle detectionsystem includes at least one particle detector, a sampling network influid communication with a or the particle detector, and means fordrawing fluid through the sampling network to a or the detector. Thesampling network includes a plurality of sample communication pathsalong which a sample can be drawn and in which the presence of particlescan be independently detected by at least one of the detectors, whereineach sample communication path includes at least one sample inlet. Eachof said inlets further belongs to one of a plurality of location groupsdefined by the physical location of the inlet. The particle detectionsystem being configured to determine whether particles are been detectedon an air sample from each sample communication path. The methodincludes:

determining a location group of inlets at which particles entered intothe particle detection system uniquely on the basis of whether particleshave or have not been detected on each sample communication path.

In one embodiment, the sampling network comprises a plurality of pipesthat respectively correspond to a sample communication path, and thestep of determining that particles have been detected at a locationgroup comprises determining that particles have or have not beendetected in fluid drawn through each of the plurality of pipes.

Further disclosed herein is an apparatus for determining the point ofentry of particles into a particle detection system of the type havingat least one particle detector in fluid communication with a samplingnetwork, and aspiration means for drawing fluid through the samplingnetwork to the or a particle detector, the sampling network including aplurality of sample communication paths in which particles can beseparately detected. The sampling network includes a plurality of sampleinlets, each inlet being a member of a location group at one of aplurality of physical locations; the apparatus further including meansfor determining a location at which particles are present on the basisof whether particles have or have not been detected on each samplecommunication path.

Also disclosed herein is a method in a particle detection system having:

-   -   at least one particle detector; and    -   a sampling system including a sampling pipe with a plurality of        sampling inlets, said sampling system being arranged to convey a        sample to be analysed from an environment surrounding the        sampling inlet via the sampling pipe to the at least one        particle detector;    -   a flow inducer arranged to cause an air sample to flow in the        sampling system to the at least one particle detector;

the method including:

-   -   measuring a first particle concentration in a sample arriving        form the sampling system;    -   varying a sampling parameter at a subset of the sampling inlets;    -   measuring a second particle concentration in a sample arriving        form the sampling system;    -   measuring a particle concentration in a sample arriving form the        sampling system; on the basis of the first and second particle        concentrations and the varied sampling parameter.

The sampling parameter that is varied can be flow rate through the firstsubset of sampling inlets. The variation can be triggered by opening orclosing valves or using a fan or other flow inducer to increase (ordecrease) flow through the subset of sampling inlets. In this case thevaried sampling parameter used to determine the measuring a particleconcentration in a sample arriving form the sampling system can be aflow rate through the subset of sampling inlets.

In some embodiments the sampling parameter that is varied is theparticle concentration drawn through the first subset of samplinginlets. The variation can be triggered by adjusting a filteringparameter applied to the first subset of sampling inlets, e.g. byinterposing or removing a filter in the flow path of air enteringthrough the sampling inlets. In this case the varied sampling parameterused to determine the measuring a particle concentration in a samplearriving form the sampling system can be a sample concentration thesubset of sampling inlets.

In some embodiments the first subset of sampling inlets is the same asthe second subset of sampling inlets. The first or second subsets ifsampling inlets may include a plurality of inlets, or may be a singleinlet.

Also disclosed herein is a method for detecting contaminant(s) in airsamples from a plurality of air intake paths, the method including:

-   -   varying the flow balance between the multiple paths by        increasing or partially reducing the flow in one or more of the        plurality of air intake paths to create a plurality of different        flow patterns;    -   measuring the contaminant level of the combined air intake paths        for each of the plurality of different flow patterns; and    -   determining the contaminant level of each air intake path by        using known, predetermined or measured values of flow rate in        each air intake path for each of the plurality of different flow        patterns,    -   wherein the number of different flow patterns created and the        number of contaminant level measurements taken are sufficient to        determine the contaminant level in each air intake path.

Varying the flow balance is preferably achieved over the plurality ofdifferent flow patterns by partial flow reduction in each of the airintake paths, in turn. In other words, if there are four air intakepaths, a first subset of the air intake paths (e.g. three paths) arepartially closed while the remaining intake path(s) remain open whilethe contaminant level is measured. Next, that first subset air intakepath is reopened and a second different subset of air intake paths ispartially closed while the remaining air intake path(s) remain open anda second measure of the contaminant level is made. This is continueduntil four different flow patterns are created while four measurementsof the contaminant level are taken.

The partial reduction in flow is preferably achieved by partiallyclosing valves in the air intake paths. So, each valve is partiallyclosed in turn while the other valves remain open. In this arrangement,the flow rate through each air intake path may not be known. Therefore,it may be necessary to measure the flow rate in each air intake path,for each of the plurality of different flow patterns.

In an alternative form, the step of varying the flow balance may beachieved by having moveable baffles within the air intake paths. Forexample, the moveable baffles may be in the form of rotatable discsmovable to a number of selectable positions. The discs have openingswhich, depending upon the selected position, create a predetermined flowrate. Thus, in this arrangement, flow rate measurements may not berequired.

In a third alternative method of varying the flow balance, each airintake path may be vented in turn while the other pipes remain unvented.Compared to the other two methods described above, this will result inan increase in air flow through each vented air intake path in turn andmay also affect the flow rate in the other air intake paths.

In a preferred form, there are as many flow patterns created as thereare air intake paths. Given that there are as many measurements ofcontaminant level as there are flow patterns, this means the number ofmeasurements of contaminant level equal the number of flow paths too.This will provide enough information to determine the contaminant levelin each air intake path, provided the flow rate in each air intake pathis also known/predetermined or measured for each flow pattern.

In some arrangements, the flow rate is measured in each air intake path.This is preferably achieved by a flow rate sensor having a reasonablyhigh degree of accuracy. In a most preferred form, flow rate is measuredby ultrasonic flow rate sensors, one in each air intake path.

Preferably, with the measured contaminant levels for each flow patternand the known/predetermined or measured flow rates in each path for eachflow pattern, a series of equations may be solved as follows:

C₁ = X₁F₁₁/(F₁₁ + F₁₂ + …  F_(1 n)) + X₂F₁₂/(F₁₁ + F₁₂ + …  F_(1n))  … + X_(n)F_(1n)/(F₁₁ + F₁₂ + …  F_(1n))C₂ = X₁F₂₁/(F₂₁ + F₂₂ + …  F_(2n)) + X₂F₂₂/(F₂₁ + F₂₂ + …  F_(2n)) + …  X_(n)F_(2n)/(F₂₁ + F₂₂ + …  F_(2n))⋮C_(n) = X₁F_(n 1)/(F_(n 1) + F_(n 2) + …  F_(nn)) + X₂F_(n 2)/(F_(n 1) + F_(n 2) + …  F_(nn)) + …  X_(n)F_(nn)/(F_(n 1) + F_(n 2) + …  F_(nn))where

X₁ . . . X_(n)=concentration in air intake paths 1 to n

C₁ . . . C_(n)=measured contaminant level of the combined air intakepaths

F₁₁ . . . F_(n1)=flow rate in pipe 1 for flow patterns 1 to n

F₁₂ . . . F_(n2)=flow rate in pipe 2 for flow patterns 1 to n

F_(1n) . . . F_(nn)=flow rate in pipe n for flow patterns 1 to n

In a preferred form, the air intake paths may be in the form of airsampling pipes. Each air sampling pipe may feed into a respective intakeport on a detector unit. The flows may be merged in a manifold, in thedetector unit prior to being fed to the detector.

The step of measuring, whether for the contaminant level or the flowrate may involve multiple readings from which an average is taken.Alternatively, any other statistical calculation may be made todetermine the central tendency of the multiple readings.

Also disclosed herein is a sensing system for detecting contaminants inair samples from a plurality of air intake paths, the system including:

-   -   a control system for controlling flow control means in each of        the air intake paths to increase or partially reduce the flow in        one or more of the air intake paths to create a plurality of        different flow patterns;    -   a detector to measure the contaminant level of the combined air        intake paths, the control system controlling the detector to        measure the contaminant level for each of the plurality of        different flow patterns;    -   the control system being further operable to determine the        contaminant level of each air intake path using known,        predetermined or measured values of flow rate in each air intake        path for each of the plurality of different flow patterns; and    -   the control system being operable to create a sufficient number        of different flow patterns and to control the detector to take a        sufficient number of measurements to determine the contaminant        level of each air intake path.

The sensing system may be in the form of a sensing unit which includesair intake ports corresponding to the number of air intake paths. Eachair intake port may be coupled to a respective sampling pipe. Each ofthe flow control means may be disposed within the sensing unit oralternatively may be disposed in a respective sampling pipe.

Preferably, the control system is able to control the measurement offlow rate.

Also disclosed herein is a sampling point for an environmental samplingsystem of the type having a at least one elongate sampling duct definedby a peripheral wall and having plurality of sampling inlets locatedalong the duct's length and extending through the wall to allow theingress of a sample, said environmental sampling system being configuredto draw a sample from the environment through the sampling inlets intothe duct and to convey the samples through the duct to an analysisdevice, the sampling point including a sample injection inlet extendinginto an interior of the duct inward of the peripheral wall thereof.

The sample injection inlet can include a pipe extending through theperipheral wall of the duct. Most preferably the pipe has an outlet ator near the centre of the duct, away from the peripheral wall of theduct.

The sample injection inlet can have its outlet facing in a downstreamdirection of flow in the duct. In a preferred form the sample injectioninlet is an L-shaped pipe, with a first inlet end for drawing a samplefrom the environment and a second, outlet end located within the ductand having an outlet facing in a downstream direction of flow in theduct. Also disclosed is a method in an environmental sampling system ofthe type having a at least one elongate sampling duct defined by aperipheral wall and having plurality of sampling inlets located alongthe duct's length and extending through the wall to allow the ingress ofa sample, said environmental sampling system being configured to draw asample from the environment through the sampling inlets into the ductand to convey the samples through the duct to an analysis device, themethod including:

-   -   providing a structure to ameliorate diffusion of at least a        front of a discrete sample portion, along the duct, as the        sample portion travels down the duct.

The structure can be a sampling point including a sample injection inletextending into an interior of the duct as described above. The structurecould also be a structure that creates turbulence within the ductconfigured to prevent laminar flow within the duct in use. For example,the structure could be a contoured or textured wall of the duct; aturbulator; a passive or active rotating element or the like.

Also disclosed herein is a sampling system for an environmental analysissystem, said sample system including at least one elongate sampling ductdefined by a peripheral wall and having plurality of sampling inletslocated along the duct's length and extending through the wall to allowthe ingress of a sample into the duct, said environmental samplingsystem being configured to draw a sample from the environment throughthe sampling inlets into the duct and to convey the samples through theduct to environmental analysis system, the sampling system furtherincluding means to ameliorate diffusion of at least a front of adiscrete sample portion, along the duct, as the sample portion travelsdown the duct. The structure can be a sampling point including a sampleinjection inlet extending into an interior of the duct as describedabove. The structure could also be a structure that creates turbulencewithin the duct configured to prevent laminar flow within the duct inuse. For example, the structure could be a contoured or textured wall ofthe duct; a turbulator; a passive or active rotating element or thelike.

The structure could extend substantially the whole length of the duct,or be localised, e.g. at or near, one or all, of the sampling inlets.

Further disclosed herein is a method in an environmental sampling systemof the type having at least one elongate sampling duct having pluralityof sampling inlets located in series along the duct's length to allowthe ingress of a sample from the environment, said environmentalsampling system being configured to draw a sample from the environmentthrough the sampling inlets into the duct and to convey the samplesthrough the duct to an analysis device, the method including: changingthe airflow characteristic in the duct to alter a local sampleconcentration at or near at least one particular sampling inlet toincrease the local sample concentration towards the sample concentrationin the atmosphere surrounding the particular sampling inlet.

Changing the airflow characteristic can include stopping or reversing adirection of flow in the duct to so that a portion of a sample adjacentthe particular sampling inlet is expelled from the sample inlet. Themethod then includes drawing an additional sample from the environmentvia the particular sample inlet. The steps of stopping or reversing adirection of flow in the duct to so that a portion of a sample adjacentthe particular sampling inlet is expelled from the sample inlet, anddrawing an additional sample from the environment via the particularsample inlet can be repeated one or more times.

The method can include oscillating the direction of flow in the ductsuch that a repeated process of expulsion and re-sampling theenvironment occurs.

The method can then include transporting the contents of the duct to theanalysis device. This transportation is preferably performed withminimal dilution of the sample within the duct, or mixing betweenlongitudinally positioned portions of the sample of the duct. Forexample the method can include; one or more of the following:

-   -   closing one or more of the sampling inlets prior to        transportation,    -   opening duct at an upstream position to provide a low flow        impedance;    -   blowing the sample along the duct from an upstream position.

An environmental sampling system of the type having at least oneelongate sampling duct having at least one sampling inlet located alongthe duct's length to allow the ingress of a sample from the environment,said environmental sampling system being configured to draw a samplefrom the environment through the or each sampling inlet into the ductand to convey the samples through the duct to an analysis device, Thesystem further including sample amplification arrangement to amelioratedilution of the sample by air flow in the duct.

The sample amplification arrangement could include a device to reverseflow direction in at least a portion of the duct. The device to reverseflow direction is preferably arranged to cause multiple reversals offlow direction to promote mixing of an air sample at or adjacent asampling inlet. The device to reverse flow could be, for example, areversible fan, bellows, reciprocating piston, vibrating membrane, orthe like.

Also disclosed herein is an environmental sampling system of the typehaving at least one elongate sampling duct having plurality of samplinginlets located in series along the duct's length to allow the ingress ofa sample from the environment that is configured to perform the abovemethod. The environmental sampling system can include one or more of thefollowing:

-   -   One or more valves to control flow along the duct and/or through        one or more of the sampling inlets;    -   fans, blowers or other flow inducing means to control flow along        the duct and/or through one or more of the sampling inlets.

A particle detection system, and preferably a smoke detection system, isalso provided that includes an environmental sampling system of theabove type to deliver air samples for analysis from a plurality oflocations.

In a preferred form the particle detection system comprises a detectionsystem according to the following aspects of the present invention. Inthis case, the accessory can comprise any one or more of: a samplinginlet or a sampling point; a valve; a filter; a duct or portion of aduct; a flow-inducing device such as a fan, piston, bellows, pump,vibrating membrane or the like; and a localisation module.

In accordance with an further aspect of the present invention there isprovided a detection system, such as a particle detection system of anyof the types described herein, for detecting an abnormal condition in anair volume, the detection system including a detector for detecting anabnormal condition of the air volume and an accessory, wherein thedetector and the accessory are in fluid communication with each otherand the air volume by an air flow path,

wherein the detector is operable to communicate, at leastunidirectionally, with the accessory through the air flow path.

The detector may be in the form of a particle detector which is used todetect an abnormal level of particles within the sampled air volume.Preferably, the type of particle detector is an aspirating smokedetector i.e. includes a fan or other type of fluid drive. Accordingly,in this preferred embodiment, the detector is able to send signals tothe accessory through the air flow path by changing the air flowcharacteristics in the air flow path. In this preferred embodiment, thatcan be achieved by adjusting flow speed or direction. Suitably, thechanges in the air flow characteristics may be detected by theaccessory, with the accessory being responsive to the detected change.Thus the change in air flow characteristics functions as a signal fromthe detector to the accessory.

Preferably the air flow path comprises an air sampling system orenvironmental sampling system as described in any one of the aspects ofthe present invention or embodiments described herein.

The accessory could comprise a detector for detecting an abnormalcondition of the air volume. The accessory detector may be any one ofthe following types: particle detector, gas detector, temperature/heatdetector, humidity detector. Alternatively, the accessory may comprise afilter, For example, the filter may be a pre-filter which is used beforeparticle detection. The accessory can be in the form of a valve or fanincorporated into the air flow path.

The air flow path suitably includes a sampling pipe network includingpipe and inlet ports. In the embodiment which utilises a particledetector, the air flow path may also include the flow path through thedetector including the aspirator i.e. the fan and the detection chamber.The exhaust from the detector also forms part of the air flow path. Theflow path through the accessory is also understood to be part of the airflow path.

The detector and the accessory may subsist as separate units along theair flow path. The accessory may be retrofittable into an existingdetection system such as a smoke detection system already having a smokedetector unit with a sampling pipe network.

Preferably the detector sends operational information to the accessory.For example, the detector may send information about the operation ofthe detector such its current mode of operation. The accessory'sresponse to the sensed information may be to adjust its settings orperform a calibration or recalibration or change its operating state.

As discussed above, one mode of communicating through the air flow pathis for the detector to cause a change in air flow characteristics whichmay be detected by the accessory. The change in air flow characteristicsmay include any aberration in the air flow which is detectable by theaccessory. This may include a change in the air flow rate or direction;or a pressure surge or wave in the air flow path. This may be created byan air flow apparatus within or within the control of the detector suchas the aspirator fan within the detector. The aspirator is preferablycontrolled by a programmable controller within the detector. Thus,suitable programming will cause the detector to send the requiredsignal(s).

The change in flow characteristics of the air flow path may vary so thatdifferent signals mean different things to the accessory. For example,rather than a single change in flow rate, there may be a plurality ofchanges such as pulses of increased flow, the number of pulsescorresponding to particular information. Alternatively, the degree ofchange in the flow rate or the actual measured flow could also be usedto denote different information.

Preferably, the accessory has a sensing system comprising one or moresensors to detect the changes in flow characteristics.

Communication through the air flow path could be by way of soundtransmission detectable by the accessory. For example a change in fannoise might be used for signalling purposes. Otherwise, sound signalse.g. acoustic, ultrasound or infrasound could be created by the detectoror other component of the system and sensed by the accessory. Suitably,the accessory has a microphone or other transducer to detect such noisesas part of its sensing system.

In an alternative form of the invention, vibrations may be created bythe detector e.g. tapping of the pipe with a suitable vibration sensorprovided in the accessory.

The detector could alternatively transmit light signals with a lightsensor on the accessory, although such a system may require a line ofsight through the air flow path.

While the above discussion has focused on unidirectional communicationbetween the detector and the accessory, bidirectional communication isalso possible. Communication from the accessory to the detector may becreated by the presence of a valve in the accessory with theconsequential effect on the air flow characteristics being detected by aflow sensor in the detector. Some accessories also incorporate a fan.This fan may also be used to have an influence in the air flowcharacteristics which may be sensed by the detector.

In accordance with another aspect of the present invention there isprovided an accessory for a detection system, the detection system fordetecting an abnormal condition in an air volume, the accessory beingfluidly connectable to the detection system and the air volume by an airflow path, wherein the accessory is operable to receive communicationtransmitted by the detection system through the air flow path. Theaccessory may include any of the features discussed above in accordancewith the first aspect of the invention.

In accordance with another aspect of the present invention there isprovided a detection system for detecting an abnormal condition in anair volume, the detection system including a detector for detecting anabnormal condition of the air volume and an accessory, wherein thedetector and the accessory are in fluid communication with each otherand the air volume, wherein the detector is operable to communicate, atleast unidirectionally with the accessory by effecting changes in airflow characteristics of the fluid communication, said changes beingdetectable by the accessory.

In accordance with another aspect of the present invention there isprovided an accessory for a detection system, the detection system forsensing an abnormal condition in an air volume, the accessory beingfluidly connectable to the detection system and the air volume, whereinthe accessory is operable to detect changes in air flow characteristicsgenerated by the detection system. Preferably, the accessory isoperationally responsive to said changes. However, the accessory mayalso be operationally responsive to a lack of any changes.

The detection system and the accessory in the preceding two aspectsabove may incorporate any of the preferred features discussed above.

In accordance with another aspect of the present invention there isprovided a method of operating a detection system which detects anabnormal condition in an air volume, the detection system including adetector for detecting an abnormal condition of the air volume and anaccessory, the detector and the accessory being in fluid communicationwith each other and the air volume by an air flow path, the methodincluding: sending a signal from the detector to the accessory throughthe air flow path, wherein the accessory is responsive to the signal ora lack of signal.

The detector may send a signal to the accessory through the air flowpath by effecting a change in the air flow characteristics.Alternatively, the signal may be sent according to any of thealternative methods discussed above in connection with the above aspectsof the invention.

The accessory response to the signal or to the lack of signal may be toshut down, go into a fault mode or adjust its operating characteristics.

In accordance with another aspect of the present invention there isprovided a method of operating a detection system which detects anabnormal condition in an air volume, the detection system including adetector for detecting an abnormal condition of the air volume and anaccessory, the detector and the accessory being in fluid communicationwith each other and the air volume by an air flow path, the methodincluding: receiving, at an accessory, a signal via the air flow path;controlling the accessory on the basis of the received signal.

The step of receiving a signal can include detecting a change in a flowparameter, such as flow rate, direction or pressure or the like, in partof the airflow path at the accessory.

Controlling the accessory can include changing at least one operationalparameter or state of the accessory in response to the received signal.Preferably the change of the operational parameter changes a flowcondition in the airflow path.

In accordance with another aspect of the present invention there isprovided a method of operating a detection system which detects anabnormal condition in an air volume, the detection system including adetector for detecting an abnormal condition of the air volume and anaccessory, the detector and the accessory being in fluid communicationwith each other and the air volume by an air flow path, the methodincluding: sensing at an accessory, a change in air flow in the air flowpath; controlling the accessory on the basis of the sensed change.

The step of receiving a signal can include detecting a change in a flowparameter, such as flow rate, direction or pressure or the like, in partof the airflow path at the accessory.

Controlling the accessory can include changing at least one operationalparameter or state of the accessory in response to the received signal.Preferably the change of the operational parameter changes a flowcondition in the airflow path.

In the above embodiments the accessory can include any one or more of: avalve, fan, flow control device, detector, filter.

As will be appreciated a system, detector and or accessory canadvantageously be used in any one of the embodiments described herein.In particular using such an accessory and method minimises thecomplexity of installation of the accessory since additionalcommunication lines need to be connected between the accessory and othersystem components.

Also disclosed herein is a method in an environmental sampling system ofthe type having at least one elongate sampling duct having plurality ofsampling inlets located along the or each duct's length to allow theingress of a sample from the environment, said environmental samplingsystem being configured to draw a sample from the environment throughthe sampling inlets into the duct and to convey the samples through theduct to an analysis device to detect the presence of a threat substancein the sample, the method including:

operating in a detection mode in which the presence and or concentrationof the threat substance is being monitored, and in the event at leastone criterion is met, the system performs the step of:

operating in a localisation mode to determine which of the samplinginlets the threat substance entered the system.

The method can include operating in a training mode to characterise asample flow through the at least one sampling duct to the analysisdevice so as to enable determination of which of the sampling inlets thethreat substance entered the system in the localisation mode.

The localisation mode can include a sample amplification phase andtransportation phase.

The localisation mode can include a purge phase.

In a further aspect there is provided a particle detection systemconfigured to monitor a series of physical locations for the presence ofparticles, the particle detection system including a particle detectorand a sampling pipe network for delivering air samples from the seriesof physical locations to the particle detector for analysis, saidsampling pipe network being arranged such that: each of said physicallocations has a sample inlet arrangement through which an air sample isdrawn into the sampling pipe network, each of said sample inletarrangements being connected to a sampling pipe at a respective samplingconnection location, wherein the average distance between the sampleinlet arrangements of neighbouring physical locations is less than theaverage distance between the sampling connection locations ofneighbouring physical locations when measured along a flow path withinthe sampling pipe network.

In the event that a sample inlet arrangement includes multiple sampleinlets the centroid of the sample inlets can be used to determine thedistance to its neighbouring arrangement(s). Similarly if the samplingconnection location of a physical location includes multiple points ofconnection to the sampling pipe the centre of the multiple points ofconnection can be used to determine the distance to its neighbour(s)along the flow path.

In some embodiments the sampling pipe passes through the regions beingmonitored to service the regions, in other embodiments the sampling piperuns near, but not through the regions (such as might be the case wherethe sampling pipe runs above a ceiling of a room, or outside anequipment cabinet which is being monitored, in order to service theregion.

In preferred embodiments the sampling pipe includes a first portionextending past or through regions being serviced by the sampling pipeand a second portion connected to the sampling pipe network upstream ofthe first portion which extends past or through at least one regionbeing serviced by the first portion. Preferably the second portionextends past or though a plurality of regions that the first portionextends past or through. Most preferably the second portions extend pastor through a majority of the regions that the first portion extends pastor through.

In some forms the first and second portions extend substantially side byside, most preferably they run parallel to each other.

In a preferred form the second portion services a location positionedbetween locations serviced by the first portion. Most preferablylocations positioned adjacent one another are alternately serviced bythe first and second portions of the pipe network. Such an arrangementacts to spread out the points of connection along flow path of thesampling pipe network, which aids in reducing ambiguity in particlelocalisation

A region should be considered to be serviced by either a given (e.g. thefirst or second) portion of the common portion of the sampling pipenetwork if a point of connection of the region's sample inletarrangement is made to the given portion of the common portion of thesampling pipe network. In another aspect there is provided a particledetection system arranged to monitor particles in a plurality ofregions, said particle detection system including a particle detectorand a sampling pipe network including a plurality of sample inlets intowhich particles are drawn for transport to the detector for analysis.Said sampling inlets being arranged to draw samples from a specificregion, wherein the sampling pipe network includes a plurality of sideby side pipes interconnected in series, wherein the sampling inletscorresponding to at least two regions that are located sequentiallyadjacent each other along the length of the plurality of side-by-sidepipes are connected to different members of the plurality of pipes. Mostpreferably when the plurality of pipes has two pipes the sampling inletsof sequentially adjacent regions are alternately connected to the firstor second pipe.

In another aspect of the present invention there is provided anapparatus comprising: a delivery system for delivering a test substanceto a particle detector arranged to protect a location; an activationmeans to activate the delivery system to deliver the test substance;

an indicator signalling the activation of the delivery system, such thatthe activation can be automatically detected by an image capture systemarranged to capture images of the location.

The apparatus can further include an interface enabling data regardingthe activation to be entered into the apparatus for storage ortransmission thereby. The delivery system can comprise at least one of:a test substance generator; a duct for delivering a test substance to athe particle detector from a test substance generator; a fan, pump orthe like to move the test substance through the apparatus to theparticle detector. The indicator preferably comprises one or moreradiation emitters configured to emit radiation for capture in an image.The apparatus can include a synchronisation port, to enable datatransfer to and/or from the apparatus to an external device, such as theparticle detection system or video capture system.

In another aspect the present invention provides a method forcorrelating an address in a particle detection system, said addresscorresponding to a physical location, with a location being monitored ina video capture system that monitors a plurality of locations; themethod comprising; causing the detection of particles in the particledetection system at the address;

indicating visually a physical location corresponding to the address;identifying the visual indication of the physical location in at leastone image captured by the video capture system;

correlating address with a location of the plurality of locationsmonitored by the video capture system.

The method preferably includes correlating the address with one or moreof: a camera that captured the at least one image in which the visualindication was identified; One or more of a pan, tilt or zoom parameterof a camera that captured the at least one image in which the visualindication was identified.

The method can include providing the correlation data to the videocapture system to enable selective capture, storage or display of imagesrelating to corresponding to an address in the particle detection systemin the event that particles are detected by the particle detectionsystem at the address. Described herein this allows video verificationof the particle detection event.

The step of indicating visually a physical location corresponding to theaddress can include, emitting radiation that can be captured andidentified in an image captured by the video capture system. This canincludes selectively activating a radiation source in a detectablepattern. For example on-off modulating a light source.

The step of causing the detection of particles in the particle detectionsystem preferably includes emitting particles at, or near, the physicallocation so as to be detected by the particle detection system at theaddress.

The step of causing the detection of particles in the particle detectionsystem at the address; and indicating visually a physical locationcorresponding to the address are preferably performed simultaneously toenable temporal correlation between images captured by the video capturesystem with a particle detection event in the particle detection system.

Most preferably the method is performed using an apparatus of theprevious aspect of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

Illustrative embodiments of the invention will now be described by wayof a non-limiting example with reference to the accompanying figures. Inthe figures:

FIG. 1 shows a particle detection system including an air samplingnetwork;

FIG. 2 shows a particle detection system employing two particledetectors to enable determination of the location at which smoke entersan air sampling network;

FIG. 3 shows a particle detection system employing a single particledetector coupled to an air sampling network having two branchesseparated by a valve;

FIG. 4 shows a particle detection system employing two particledetectors coupled to a single air sampling pipeline;

FIGS. 5 and 6 graphically illustrate a timing of events as measured atrespective detectors (or branches) of a particle detection system;

FIG. 7 illustrates another embodiment of a particle detection systemthat is used to determine a location particles entering the system;

FIG. 8 illustrates a particle detection system including a samplingsystem including a plurality of valves, for altering a samplingparameter of the sampling system [to implement an embodiment of oneaspect of the invention];

FIG. 9A illustrates a particle detection system including a samplingsystem including a plurality of filters which are configured to alter asampling parameter the sampling system [to implement an embodiment ofone aspect of the invention];

FIG. 9B illustrates a filter and valve arrangement used in the system ofFIG. 9A;

FIG. 10A is a schematic diagram of a particle detection system accordingto a preferred embodiment of the present invention;

FIG. 10B is a schematic diagram of a portion of the particle detectionsystem of FIG. 10A;

FIG. 10C is a schematic view of the portion of the particle detectionsystem as per FIG. 10B, except with one of the valves in a partiallyclosed position; and

FIG. 10D is a schematic view of the portion as per FIG. 10C, except thatone of the other valves is partially closed;

FIG. 11A illustrates a particle detection system;

FIG. 11B is a graph illustrating diffusion of a front of a sampleportion as the sample portion travels down a duct;

FIG. 11C illustrates a flow speed profile within the sample duct of FIG.11A;

FIG. 12 illustrates 3 sampling points according to different embodimentsof the present invention, that may ameliorate the effect of thediffusion illustrated in FIG. 11B;

FIGS. 13A to 13D are examples of turbulators that may ameliorate theeffect of the diffusion illustrated in FIG. 11B;

FIG. 14 illustrates a particle detection system including an airsampling network that is connected to bellows that can be used tooscillate the direction of sample flow within the air sampling duct tocounteract sample dilution by other sampling inlets within the particledetection system;

FIGS. 14A to 14E illustrate an exemplary system that uses a vibratingmembrane to perform sample amplification in a manner analogous to thatof FIG. 14;

FIG. 15 illustrates a particle detection system including an airsampling system that has an upstream fan that can be used to counteractsample dilution by other sampling inlets within the particle detectionsystem.

FIG. 15B illustrates a particle detection system similar to that of FIG.15, which has been augmented with a sample flushing system.

FIG. 16 illustrates a particle detection system having an air samplingsystem including a valve upstream of the sampling inlets that can beused to open the end of the sampling duct to enhance transport of samplein the duct to the particle detector for analysis;

FIG. 17 illustrates a variant of the system of FIGS. 14A to 14E;

FIG. 18 illustrates a particle detection system including an airsampling network that has a sample amplification arrangement comprisinga plurality vibrating membranes; and

FIG. 19 illustrates another particle detection system including an airsampling network with branched sampling pipes and which has a sampleamplification arrangement comprising a plurality vibrating membranes.

FIGS. 20A and 20B illustrate a variation on the systems of FIGS. 14 and15 respectively, which include a dedicated localisation module.

FIG. 21 illustrates a particle detection system according to anembodiment of the present invention, which is arranged to detectparticles in a series of regions.

FIGS. 22 and 23 illustrate further two embodiments of a system accordingto the invention that are arranged to detect particles in a series ofregions.

FIG. 24 illustrates a particle detection system incorporating videoverification using a video security system.

FIGS. 25 and 26 illustrate exemplary user interfaces used for videoverification in the system of FIG. 24.

FIG. 27 is a schematic diagram of an apparatus used for commissioningand/or testing of a system of the type illustrated in FIG. 24.

FIG. 28 is an exemplary accessory, in this case a valve, which isarranged to sense a change or condition in flow in the air flow pathfrom another system component and control its operation in response tothe sensed change or condition.

FIG. 29 illustrates a particle detection system incorporating anaccessory as described in connection with FIG. 28.

FIG. 30 illustrates an embodiment of a localisation module.

FIG. 31 illustrates another embodiment of a localisation module to whichmultiple sampling pipes can be connected.

FIGS. 32 and 33 illustrate additional embodiments of accessories similarto that of FIG. 28.

DETAILED DESCRIPTION OF THE EMBODIMENTS

FIG. 1 shows a particle detection system including a particle detector11 in fluid communication with a sampling network 28. The samplingnetwork includes a plurality of inlets 29 through which air is drawn. Anaspirator 16 draws air into the sampling network 28 through inlet 21 andalong into a particle detection chamber 14. Air sample exits thedetection system through outlet 22.

The detector includes a flow sensor 24. In a preferred embodiment of thepresent invention, an ultrasonic flow sensor as described in WO2004/102499 is employed. This sensor enables volumetric flowmeasurements to be made. The flow sensor 24 provides an indication ofthe volume of air flowing into the particle detector 10 from thesampling network 28 per unit time. The output of the flow sensor 24 maybe used to infer, for example, when flow faults e.g. a blockage of thesampling network 28 or reduced aspirator performance, has occurred.

The system 10 also includes a controller 40 for determining the level ofparticles in the air sample based on the detector's 14 output and applyalarm and fault logic to the detector output alert a user to thepresence of particles and the operating state of the system. A typicalinstallation of a Vesda or ICAM smoke detector, from Xtralis Pty Ltd.would be an example of a system of this type.

Such a detection system can be applied in an embodiment of the presentinvention to additionally determine the point of entry of particles intothe air sampling network 28.

FIG. 2 shows two particle detectors 202 and 204, each particle detectorbeing of the type illustrated in FIG. 1. Each detector is connected to arespective pipe of sampling network 203 and 205 respectively. Thesampling networks 203 and 205 are effectively parallel and configured tomonitor the same area. Each detector is also connected to a control unit207, containing a microcontroller 209. Pipe 203 has a plurality of airinlets 206-216. Similarly, pipe 205 has a plurality of air inlets218-230. Each air inlet from pipe 203 can be paired with an inlet fromits parallel air pipe 205. At the time of installation, each inlet frompipe 203 is positioned to be close to a corresponding inlet from pipe205. The inlets are therefore arranged in pairs. For example, air inlet206 of pipe 203 and air inlet 218 of pipe 205 are together labelled airsampling inlet pair 232, because air inlet 206 and air inlet 218 areplaced in close physical proximity. For example each pair of inlets maybe located in the same room of a row of offices, or even be attached toa common sampling point.

In normal operation, the aspirator of particle detector 202 draws airpipe 203. The aspirator of particle detector 204 draws air through pipe205. As each particle detector draws air, the scattered light or “smokelevel” is measured, and reported to the control unit 207. Themicrocontroller 209 of the control unit 207 stores the reported smokelevels in its internal memory.

In the event that smoke enters the air sampling network at air samplinginlet pair 232, the distance that smoke must travel to reach particledetector 202 from air inlet 206 is much smaller than the distance thatsmoke must travel to reach particle detector 204 from air inlet 218.Accordingly, particle detector 202 will register an increased smokelevel due to smoke entering air sampling inlet pair 232 before particledetector 204.

When the detected smoke level of one of the detectors 202,204, sayparticle detector 202, surpasses a predetermined threshold (which mayalso be an alarm threshold or not), the microcontroller begins tomonitor the volume of air that has been drawn through one or both of thedetectors. Because the smoke introduced at air inlet 218 must travelalong the length of sampling pipe 205 before it can be detected atdetector 204. After the particle detector 204 has drawn some volume ofair, particle detector 204 will record an increased smoke level similarto that seen by particle detector 202. When this increased smoke levelis recorded, the microcontroller 209 finishes monitoring the volume ofair that has been drawn through detector 204. This final volume can beused to determine the sampling hole through which the smoke entered theair sampling pipe.

Because the flow sensor e.g. 24, outputs volumetric rate of flow, thevolume of air passing through the detector is determined by integratingthe output of the flow sensor over time. For example, the flow rate maybe output one or more times per second by the sensor. These volumes canbe accumulated either in the detector itself or at the microcontroller209 to determine the total volume of sample air that has flowed.

The microcontroller 209 then uses the determined volume of air drawn bydetector 204 to infer the sampling inlet pair through which the smokeparticles were introduced. In one embodiment, the microcontrollerachieves this by consulting a lookup table such as the one below:

Volume Air Inlet Pair −5 L Pair 1 −3 L Pair 2 −1 L Pair 3   1 L Pair 4  3 L Pair 5   5 L Pair 6

The lookup table contains measured volumes mapped back to acorresponding sampling hole pair. Each volume corresponds to the volumeof air that is drawn through the second detector before particles aredetected by it. The negative and positive values indicate which detectorof the pair 202 or 204 measure the volume. In this case a negative valueindicates that the detector 202 measures volume.

For example, the microcontroller 209 may measure a volume of 112 mL ofair drawn through detector 204 in the time between a smoke detectionevent by detector 202 and a subsequent detection event by detector 204.The row of the table that has a volume most closely corresponding to thevolume is the fourth row, and corresponds to Pair 4. Pair 4, in turn,corresponds to air inlet pair 238. Had the measured volume instead been−112 mL, the closest table row would have been the entry for −100 mL,and Pair 3 (air inlet pair 236) would have been determined as the pointat which smoke entered the system.

As will be appreciated, instead of measuring volume directly a valuethat corresponds to volume could be used in other embodiments of thepresent invention. For example the amount of air sample that has passedthrough the system can be determined by measuring a parameter other thanvolumetric flow rate, for example, if a mass flow sensor is present inthe detector the output of such a sensor is able to be used in anembodiment of the present invention as it is related to volume by acorrection factor that corrects for the temperature or density of thefluid.

Other physical parameters may also be used, including but not limited toas length, pressure or temperature or a count of volume-related events.For example, the time variable speed of the sample flow can be measured(e.g. in ms⁻¹) at location and accumulated (e.g. summing or integrationetc.) to determine an amount of air that has passed through the systemin the form of a “length”. Volume could also be represent as a “length”by using the air sample (or known proportion of it) to displace apiston. The total displacement of the piston by the collected sample (orfixed proportion thereof) will represent a measure of the amount of airthat has passed through the system, alternatively for a small cylindersize the a number of cycles of the piston could be counted to yield annumerical value corresponding to the volume of air sample that haspassed through the system.

To give an example in which the physical parameter being used todetermine an amount of air passing through the system is pressure ortemperature, consider a system in which the air sample (or a knownproportion of the air sample volume) is captured in a first chamber of aclosed system, the actual volume V₁ (or pressure if volume if fixed) ofthis amount of air may never be known. However if the temperature T₁ andpressure P₁ (or volume if pressure is fixed) of the captured sample ismeasured. The captured sample is then moved to a second camber of known,volume V₂ and the new temperature T₂ and pressure P₂ are related to theinitial volume by Boyle's law. By controlling one the either pressure ortemperature to be held constant during the transfer of the sample (orsample portion) to the second chamber a temperature or pressure can beused as an amount that relates to volume of sample air that has passedthrough the system.

If a measurement of a value, such as mass, pressure, temperature andlength, or other physical parameter that might be measured and which istolerant to variable flow rate, is used in place of volume, the look-uptable may alternatively map those other physical parameters directly tothe air inlet pair number, without having to undertake the intermediatestep of calculating the volume.

Once the air inlet pair number has been determined, the air inlet pairnumber can then be communicated to a secondary device, such as a FireAlarm Control Panel (FACP) or displayed to the user, to enable thelocalisation of the fire.

The lookup table can be created during the commissioning of the system,for example, by introducing smoke to each sample inlet pair andmeasuring the volume of air drawn before detection. As will beappreciated, if smoke has entered at sampling pair 232, there will be avery large volume of air drawn by detector 204 in the period afterdetection by detector 202 while detector 204 waits to detect theincreased smoke level. Conversely, if smoke entered the system throughsampling pair 242, detector 204 would detect an increased smoke levelbefore detector 202, detector 202 drawing a very large volume of airwhile waiting to detect the increased smoke level. If smoke were toenter the sampling network toward the middle, for example at sample pair236, although detector 202 would detect an increased smoke level first,the volume of air drawn before detection by detector 204 would berelatively smaller than in either of the first cases, since by the timeof detection by detector 202, smoke will have already been drawn asubstantial distance toward detector 204.

A person skilled in the art will appreciate that in the presentconfiguration, where the sampling pipe network length is large, andtransport time of particles through the sampling network is large, itwill be possible to detect the presence of smoke before determining thelocation of smoke. For example, in the event that smoke is introduced atsampling inlet pair 232 of FIG. 2, smoke entering sampling hole 206 willquickly proceed to detector 202, and be detected. Detector 202 canimmediately raise an alarm, despite the fact that smoke has not yet beendetected by detector 204. Accordingly, where regulations prescribe thetime by which smoke introduced to a sampling hole must be detected, thisparticular configuration is capable of detecting and reporting upon thepresence of fire upon detection of smoke particles. Determination of thegeographic location of the fire can then proceed in the mannerpreviously described using a threshold level that is not an alarm level.

Accordingly, in a preferred form, the threshold used for determining anaddressing event for each detector is higher than the lowest alarm(e.g.: a pre-alarm) threshold. A preferred embodiment waits until ahigher level of particles is detected before attempting addressing.

In one embodiment, instead of employing a lookup table, the volumeoffset is multiplied by a constant to determine the distance along thesampling network at which smoke particles entered the system. In anotherembodiment, the volume offset is used as a variable in a function, whichwhen evaluated, yields an estimate of the distance along the samplingnetwork at which particles entered. In yet another embodiment, thevolume offset is used as an index into a lookup table, the resultinglookup value being an estimate of the distance along the pipe. Inpreferred embodiments, the multiplicative constant, function, or lookuptable described immediately above is determined at the time ofcommissioning by introducing smoke to each sampling hole pair andmeasuring the resulting volume offset to generate calibration data. As aperson skilled in the art will appreciate, it may be possible to inferresults for a subset of sampling holes by introducing smoke to anothersubset of holes, and relying upon the known distribution of samplingpairs in the sampling network.

As a person skilled in the art will appreciate, modifications of theinvention can be adapted to determine, for example, the spread of afire. The information reported by the system may be a distance along thesampling network at which particles appear to have entered, althoughthis distance may not correspond to a sampling inlet pair.

The calculated distance or air inlet may be presented directly to an enduser. The calculated distance or air inlet may also be communicated toanother system, such as a fire alarm control panel (FACP). Where a firealarm control panel has been designed to receive data from a system ofaddressable point detectors rather than a single aspirated smokedetector having multiple sampling points, the present system maycommunicate the calculated distance or inlet to the fire alarm controlpanel in a way which mimics a system of addressable point detectors,thereby utilising the FACPs understanding of geographic location offires without actually utilising individual addressable point detectors.

FIG. 3 illustrates an alternative embodiment of the invention thatemploys a single particle detector attached to an air sampling networkcomprising two pipes 303 and 305 and a valve 304. In normal operation,air is drawn through pipe 303. When smoke detector 202 detects smokeabove a predetermined threshold, valve 304 is moved to obstruct pipe303,and to allow air to flow through pipe 305, and the microcontroller 309begins to record the volume of air drawn through detector 302. Whensmoke particles are detected by detector 302, microcontroller 309finishes recording the volume of air drawn though detector 302. Thevolume of air passing through air sampling network 305 and into particledetector 302 prior to again detecting particles is then used to inferthe point at which smoke particles enter pipe 305, using any of themethods herein described.

FIG. 4 shows yet another approach which employs two particle detectorsattached to a single air sampling network. Initially, smoke detector 402operates and smoke detector 404 is inoperative. Smoke enters the systemthrough air inlet 408. The smoke is drawn through the air samplingnetwork, and detected by smoke detector 402. The determination of asmoke detection event triggers smoke detector 402 to become inoperative,smoke detector 404 to become operative, and microcontroller 409 to beginrecording the volume of air drawn through detector 404. The aspirator ofsmoke detector 404 draws air along air sampling network 403 in adirection opposite to the initial flow direction caused by the aspiratorof smoke detector 402. If smoke enters only through a single air inlet408, smoke detector 404 cannot detect smoke until smoke from air inlet408 reaches it. According to the present invention, the volume of airdrawn by detector 404 after the initial detection by smoke detector 402and up until subsequent detection of smoke by detector 404 is used todetermine the air inlet through which smoke particles enter air samplingnetwork 403, using any of the methods herein described.

The inventors have realised that it can be advantageous to use thevolume of air drawn through the system or corresponding values todetermine the point of entry of particles into the air sampling system.Moreover, by measuring volume rather than time, certain disadvantages orproblems associated with reliance on measurement of time may beameliorated. For example, it is known that with usage the samplinginlets gather dirt and get constricted, resulting in greater pressuredrop and less flow of air. This means changing transport time for airsamples over the life of the system. However the volume of air displacedto get a sample to the detector is relatively constant over time whichmakes the correlation between displacement volume and address morestable than transport time. Moreover if there are delays in opening avalve or beginning an aspirator, or the fan starts more slowly thanexpected the volume of air drawn through the system before particles aredetected a second time is likely to be relatively unchanged, as comparedto time based systems. Advantageously volume-based addressing systemsmay be able to be operated independent of the flow rate or over a rangeof variable flow speeds, enabling techniques such as those describedbelow, in which the system opens up an end cap to speed up the flow of asample to the detector.

Other types of flow sensor can be used in embodiments of the invention,for example a mass flow sensor, which provides an indication of the massof air moving past the sensor over time. However, because mass flowsensors are insensitive to the density of the air they measure, otherinformation such as the temperature of the air is required in order todetermine the volume of the air moving past them.

A further difficulty that can arise in implementing embodiments of theabove invention and that of the prior art is the potential difficulty inreliably determining that two equivalent smoke detection events hasoccurred, for example noise introduced prior to conversion of a signalfrom analogue to digital form may frustrate the process of determiningwhen smoke is detected by detector 202, or detector 204. The inventorshave devised an improved process that avoids or ameliorates thisdrawback.

A smoke detection system such as that of FIG. 2 produces two distinctdata sets or “particle detection profiles”. One data set is drawn fromparticle detector 202. The second data set is drawn from particledetector 204. Each data set contains a series of measured smoke levels.The data set may also contain information regarding the volume of airflowing through the detector, or a time at which a particle smoke levelwas measured.

In the following example, we will describe a system that monitors smokelevels over time. A person skilled in the art would appreciate that themethod can be adapted to measuring smoke levels compared to the volumeof air drawn by the system (as described above), however forillustrative purposes, we presently describe the system in relation to aseries of measured smoke levels taken at various times.

FIG. 5 illustrates a particle detection profile. Detected smoke level isrepresented along its vertical axis. Time is measured along thehorizontal axis. The smoke levels are those measured by detector 202 ofFIG. 2. FIG. 6 shows a second particle detection profile. It is similarto that of FIG. 5, except that it relates to smoke levels measured bydetector 204.

Comparing the figures, detector 202 detected a smoke level that reacheda maximum at time 200, at which time it was deactivated and the particledetection output returned substantially to zero. Detector 204 detects amaximum smoke level at time 300. The different times are at leastpartially attributable to the additional distance along the samplingnetwork 205 that smoke reaching detector 204 must travel. It would bepossible to use the difference between the time of each maximum or thedifference in time at which each profile crosses some predeterminedthreshold e.g. a smoke level of 150 on the vertical axis (which may bedifferent to the alarm thresholds in use), to estimate the air inletthrough which smoke entered the particle detection system. However, morepreferably a cross correlation can be calculated using the dataillustrated in FIGS. 5 and FIG. 6.

For real and continuous functions f and g, the cross-correlation iscalculated according to the formula:(f * g)(t)=∫_(−∞) ^(∞) f(τ)g(t+τ)dτ

A person skilled in the art will appreciate that this equation can beadapted for use with discrete measurements, such as the smoke levelsdetected in the present systems. For example, such a system can beimplemented in hardware by temporarily storing a particle detectionprofile of each detector data in a respective buffer, e.g. a ringbuffer. The buffers may be chosen so as to store data such that thelongest possible offset measurable by the system can be accuratelycalculated. The cross correlation at a point can then be calculated bymultiplying each pair of data elements in turn, and adding them, asdescribed by the equation above. This process can then repeated for eachpossible offset t, to determine the overall cross-correlation function.The cross correlation function can then be used to estimate of the timeoffset between two particle detection events. This can in turn be usedto infer through which inlet pair the particles entered the samplingpipe network. In some embodiments, information from thecross-correlation function is used to locate further geographiclocations at which smoke may have entered the system.

In one embodiment, multiple peaks of the cross-correlation function areidentified. A list of time offsets is calculated based upon the locationof each peak and its corresponding cross-correlation value. The timeoffsets are used to infer the geographic location of the source ofsmoke. This can be used to potentially infer multiple locations at whichfire occurs.

FIG. 7 illustrates a detector particle detection system 700 thatincludes a particle detector 702 in fluid communication with an airsampling network in the form of pipes 704, 706, 708 and 710. Each pipeincludes a plurality of inlets, arranged into sampling inlet groups 712to 740. Each sampling inlet group corresponds to a physical address,e.g.: a room or location that is serviced by the detector. Each sampleinlet group includes between one and four air inlets.

The particle detector is connected to each pipe, and configured toprovide an indication to a controller whether particles have beendetected in fluid drawn through each pipe. The detector 702 could forexample be four VESDA smoke detectors (from Xtralis Pty Ltd) detectorscoupled to a central controller or a detector capable of independentlydetecting smoke on up to 4 pipes.

Each of sampling inlet groups 712 to 740 comprises one, two, three orfour individual sampling inlets. The inlets are arranged into groupssuch that the same pattern does not occur twice. For example, samplinginlet group 730 includes an inlet on each pipe but no other groupincludes an inlet on each pipe. Sampling inlet group 712 includes aninlet only on pipe 710, but no other sampling inlet group includes onlya hole on pipe 710. In the example of FIG. 7 the inlets are arranged ingroups corresponding to a 4-bit Gray code.

Consistent with the discussion previously in relation to FIG. 2, at thetime of installation, the inlets from each group are positioned close toone another. In the event that smoke enters the sampling network at aparticular inlet, smoke should enter each of the pipes for which thereis an inlet present in that group. For example, if smoke enters thesampling network near the location of sampling inlet group 730, onewould expect smoke to enter each of the four pipes 704, 706, 708 and 710at that location. Conversely, if smoke enters the sampling network atsampling inlet group 712, one would expect smoke to only enter pipe 710,since at that location, no other pipe includes an inlet. Upon detectionof particles in the samples drawn into the individual pipes 704,706,708, 710, the particle detection system is able to determine thepoint of entry of smoke into the sampling network based upon the patternof detection across the pipes 704, 706,708, 710.

The table of FIG. 7 more completely illustrates the possiblecombinations of particle detection states across the four pipes andtheir corresponding particle detection locations. It is useful to beginby defining a nomenclature for expressing the indicated smoke levels.For present purposes, we will use a four binary bits to correspond tothe detected smoke levels for each of pipes 704, 706, 708, and 710respectively. For example, the indication ‘1111’ corresponds todetection of smoke at some threshold level, in air drawn from each ofpipes 704, 706, 708, and 710. The indication ‘1100’ would refer todetection of smoke in air drawn from each of pipes 704 and 706. Theindication ‘1010’ would refer to detection of smoke in air drawn fromeach of pipes 704 and 708. Accordingly, each of these four bitindications can be treated as an address that corresponds to a location.There are fifteen non-zero four bit numbers. Accordingly, these fifteennumbers can be used to distinguish fifteen separate locations. The tableof FIG. 7 lists each of the possible fifteen non-zero binary numbers inthe column ‘Gray Code’ address. Alongside each binary number is one of15 locations in the ‘Location’ column. The ‘Smoke Detected’ column showswhether smoke had been detected at the assigned threshold level at pipe.

There is a large number of possible ways of allocating addresses to eachlocation. For example, in some embodiments, each successive locationfrom 1 to 15 may take a subsequent binary number, in a manner similar toordinary counting. Accordingly to this scheme, location 1 would have theaddress ‘0001’ (which is a binary representation for the decimal number‘1’) and location 2 would have the address ‘0010’ (which is a binaryrepresentation for the decimal number ‘2’). In this scheme, location 15is given the binary address ‘1111’, which is a binary representation forthe decimal number 15.

However, the illustrated embodiment uses a different method ofallocating addresses, called a ‘Gray code’. In the illustrated gray codeof FIG. 7, the location 1 is given the address ‘0001’. Location 2 isgiven the address ‘0011’ (which corresponds to the binary for thedecimal number ‘3’). Location 3 is given the address ‘0010’ (whichcorresponds to the binary for the decimal number ‘2’). This sequence ofnumbering has a special property when each of the binary representationsis considered. In particular, each pair of adjacent locations has abinary representation that differs by precisely one bit. For example,location 4 has the address ‘0110’, whereas location 5 has the address‘0111’, and so only the fourth bit of each number differs. Similarly,location 11 has the address ‘1110’ whereas location 12 has the address‘1011’, and so these also differ by their second bit only.

The way in which addresses are chosen may influence performance in thepresence of detection errors. In particular use of a Gray code schememay be, more robust to addressing errors than a straight “counting”address scheme in which successive locations are addressed by successivebinary numbers. To illustrate this point, in a system that adopts thegray code numbering as described in FIG. 7, there is roughly a fiftypercent chance that for a single bit error the determined location ofthe fire will be a location adjacent to the actual location of smoke,since the address of each adjacent location differs by a single bitonly.

A person skilled in the art would appreciate that judicious selection ofthe sample inlet groups and increasing of the number of pipes feedingthe detector can result in increased redundancy for the purpose of thelocalizing decision. In practical terms, the introduction of thisredundancy may be such that, for example, simultaneous entry of smoke atmultiple sample inlets can be distinguished, or alternatively, such asystem may simply provide greater resilience to error.

FIGS. 8 and 9 show two embodiments of a further mechanism for providingaddressability within an aspirated particle detection system of the typedescribed in FIG. 1.

Turning firstly to FIG. 8, which shows a particle detection system 800,including a particle detector 11, coupled to an air sampling system 26.The air sampling system 26 includes a sampling pipe 28, including fivesample points 29. As described in relation to FIG. 1, the aspirator ofthe particle detector 11 draws air samples in through the sample inlets29, which then travel along the pipe 28 and into the detector 11 foranalysis. In this embodiment, each sampling hole 29 additionallyincludes a valve 802. Each valve 802 is independently able to adjustflow through its respective sampling hole 29. The valves are controlledby the central controller of the detector 11, and are configured to beopened and closed under the control of detector 11. In some embodimentsthe valves 802 can receive sense the need to change state byinterpreting glow changes as signals from the detector 11 in a mannerdescribed in more detail in connection with FIG. 28.

The purpose of the valves 802 on each sampling inlet 29 is to enable thesmoke detector 11 to vary one of its systems' sampling parameters inorder to assist in determining which of the sampling inlets 29 particlesof interest have entered the system 800 through. Upon an initialdetection of particles of interest by the detector 11, at apredetermined threshold level, the detection system 800 goes into thelocalisation routine. In this routine, the detector 11 causes the valves29 to vary a sampling parameter, in this case flow rate, of air enteringthe sampling inlets. This variation may be performed on an inlet byinlet basis, or in groups of multiple inlets. After each variation inflow rate, a new particle concentration measurement is made. The initialparticle concentration measurement and the second particle concentrationmeasurement along with a variation parameter can then be used todetermine which of the sample inlets particles of interest enteredthrough.

This works because the particle level detected at the detector 11 is aweighted sum of particle concentrations and flow rates of the sampleflow at each individual inlet 29. By varying the smoke level or flowrate through the sampling inlets, it is therefore possible to solve theset of simultaneous equations to determine the particle level enteringany one sample inlet or group of inlets.

To illustrate a simple example, consider a smoke detection systemincluding a smoke detector and a sampling network having a pipe with twosample inlets.

In this example, the level of smoke detected when all valves are open isgiven by the following equation:

${DetectorSmokeAllValvesOpen} = \frac{{{Smoke}\; 1*{flow}\; 1} + {{Smoke}\; 2*{flow}\; 2}}{{{flow}\; 1} + {{flow}\; 2}}$

Where, DetectorSmokeAllValvesOpen is the total smoke detected by thesmoke detector;

Smoke1 is the smoke level in the sample entering sample inlet 1;

flow1 is the flow rate of the sample entering through sample inlet 1;

Smoke2 is the smoke level entering the sample inlet 2; and

flow2 is the flow rate through sample inlet 2.

Now, when the first sample inlet is closed by its valve, the weightedsum of smoke arriving at the detector becomes:

${{DetectorSmokeValves}\; 1{Closed}} = \frac{{{Smoke}\; 1*0} + {{Smoke}\; 2*{flow}\; 2}}{0 + {{flow}\; 2}}$

It will be noted that this weighted sum is identical to equation 1,except that flow1=0, because the valve on sample inlet 1 has been closedfully.

We are now in a situation where we can solve these equations for Smoke1,to determine the amount of smoke that has entered through sample inlet1, as follows:

${{Smoke}\; 1} = \frac{\begin{matrix}{{{DetectorSmokeAllValvesOpen}( {{{flow}\; 1} + {{flow}\; 2}} )} -} \\{{DetectorSmokeValves}\; 1{{Closed}( {0 + {{flow}\; 2}} )}}\end{matrix}}{{flow}\; 1}$

Thus, if we know flow1, flow2 and the change in flow, we can solve theequation and determine what smoke level entered at sample inlet 1. Thisprinciple also works in the event that the valves 802 only partiallyrestrict flow through their respective sampling hole when they areclosed, so long as it is possible to determine the flow rate at eachsampling inlet 29. In order to allow flow rate to be detected, thesystem 800 includes a flow sensor 804 at each sample inlet 29. The flowsensor 804 could be a high sensitivity flow sensor, such as anultrasonic flow sensor or a lower cost thermal flow sensor of the typewhich will be known to those skilled in the art.

In some embodiments, the valves 802 will not reduce the flow ratethrough their respective sample inlet to 0, but will only reduce it bysome fraction. The following equation demonstrates how in a two holesystem, as described in relation to the last example, smoke levelthrough sample inlet 1 (Smoke1) may be calculated if valves are used toreduce the flow rate through their respective sampling holes to halftheir previous flow rate.

${{Smoke}\; 1} = \frac{\begin{matrix}{{{DetectorSmokeAllValvesOpen}( {{{flow}\; 1} + {{flow}\; 2}} )} -} \\{{DetectorSmokeValves}\; 1{{Closed}( {{0.5\;{flow}\; 1} + {{flow}\; 2}} )}}\end{matrix}}{0.5\mspace{11mu}{flow}\; 1}$

In a further embodiment of the present invention, instead of varyingflow rate through the sample inlet to solve the simultaneous equations,it is possible to vary the level of smoke entering each of the inlets.This can be achieved by selectively interposing a filter into the flowpath through each of the sample inlets 29. An example of such a systemis shown in FIGS. 9A & 9B. The system of FIG. 9A 900, includes adetector 11 connected to a sampling network 26, which includes samplingpipe 28, into which air samples are drawn through plurality of sampleinlets 29. Each sample inlet additionally includes a selectable filterarrangement 902, which is shown in more detail in FIG. 9B. Theselectable filter arrangement 902 presents an air sample inlet 904(equivalent to inlet 29) at one end, and a sample outlet 906 at theother. The air sample inlet 904 is open to the environment, and allowsan air sample from the environment to be drawn into the selectablefilter arrangement 902. The sample outlet 906 is connected to thesampling pipe 28. Inside the selectable filter arrangement 902 are twoflow paths, one path, 908, which is unfiltered, and another 910 whichincludes a filter 912. The selectable filter arrangement 902additionally includes a valve 914. The valve 914 is moveable between thefirst position in which it blocks the filtered flow path 910, and asecond position in which it blocks the unfiltered flow path 908. Aftersmoke has initially been detected by the detector 11, at a thresholdlevel, and the detector goes into its localisation mode, in which itattempts to determine which sample inlet 29 particles have entered thesystem from, the valve 914 is triggered to switch between the firstposition in which particles drawn in through the inlet 904 are allowedto pass through to the outlet 906, into a second position, in which anyparticles entering the inlet 904 are removed from the airflow passingout of the outlet 906 by the filter 912. In a preferred form, the filter912 is a HEPA filter or other high efficiency filter which will removesubstantially all particles from the airflow.

The sampling point 29, and in this case the selectable filterarrangement 902 includes a flow sensor 916 to measure flow rate enteringthe sampling point 29.

The selectable filter arrangement 902 can be configured to communicatewith the detector 11 via the airflow path of the system 900. In anexample such as this the communication protocol used by the detector 11will need to signal such that each selectable filter arrangement 902 canbe individually addressed or each selectable filter arrangementprogrammed to operate with a co-ordinated timing. More details of anexample communication method are described in connection with FIG. 28.

As will be appreciated, a similar set of equations to that described inconnection with the first example, can be applied to the system of thetype illustrated in FIG. 9A and 9B.

For a two hole system, as discussed above, the level of smoke arrivingat the detector when all sample inlets have their input unfiltered canbe expressed with the following equation:

${DetectorSmokeAllUnfiltered} = \frac{{{Smoke}\; 1*{flow}\; 1} + {{Smoke}\; 2*{flow}\; 2}}{{{flow}\; 1} + {{flow}\; 2}}$

Where, DetectorSmokeAllUnfiltered is the level of smoke received at thedetector when all flows are unfiltered, and all other terms are asdescribed above in connection with equations 1 through 4.

After the selectable filter arrangement of the first sampling hole ismoved into its filtered mode, the weighted sum expressing the level ofsmoke received at the detector is expressed as follows:

${{DetectorSmokeFiltered}\; 1} = \frac{{0*{flow}\; 1} + {{Smoke}\; 2*{flow}\; 2}}{{{flow}\; 1} + {{flow}\; 2}}$

Where, DetectorSmokeFiltered1 is the level of smoke received at thedetector when the flow-through sample inlet 1 is fully filtered.

Solving these equations simultaneously yields the following equation,from which the level of smoke arriving at sample inlet 1 can bedetermined.

${{Smoke}\; 1} = \frac{\begin{matrix}{{{DetectorSmokeAllUnfiltered}( {{{flow}\; 1} + {{flow}\; 2}} )} -} \\{{DetectorSmokeFiltered}\; 1( {{{flow}\; 1} + {{flow}\; 2}} )}\end{matrix}}{{flow}\; 1}$

In order to handle increasing or decreasing smoke levels which maychange reliability of this type of localisation process, the sequence oftaking measurements in a first state and a second state can be repeated,and equivalent states averaged over a number of cycles. For example, thefirst measurement with all valves open can be taken followed by a smokelevel measurement with the varied parameter, followed again by anequivalent initial reading with all valves open again. The two valveopen measurements can then be averaged and used in subsequentcalculations.

Further variation on the present systems can be implemented whereinstead of constricting or reducing the flow through each of thesampling points, the flow rate at the sampling points is increased,either by opening a valve, to increase the size of the sampling hole todecrease its flow impedance, and thereby increase the proportion of thetotal airflow from the system which is drawn through that samplingpoint, or by putting a fan at each sampling point and actuating orvarying the speed of the fan to either increase or decrease the flowthrough the sampling point by a known amount.

The above embodiment has been described with a simple two inlet system.However, as will be appreciated, an as described in FIGS. 8 and 9A,systems are likely to have more than two sampling inlets. In suchsystems it is possible to scan through each of the inlets individuallyand vary the sampling parameter at only one inlet at a time. However, itmay be beneficial to perform the variation in a grouped manner in whicha subset of the total number of inlets have their sampling parametersadjusted in each measurement cycle. In some cases it may be possible tovary the sampling parameters of all sampling inlets by a differentialamount in order to determine the contribution of each. As will beappreciated, the more inlets in the system that there are, the moretimes the process of varying sampling parameters and remeasuringparticle concentration needs to be performed in order to collectsufficient data to solve the necessary set of equations.

The concept described in connection with FIGS. 8, 9A and 9B can beextended more generally to a method for detecting contaminant(s) in airsamples drawn from a plurality of air intake paths and determining thecontaminant level in each. For example the methods could be applied toan aspirating particle detector that is coupled with a sampling networkhaving a plurality of air sampling pipes feeding to the single detector,where the contribution from each pipe or branch of the sampling systemis to be determined. FIG. 7 describes a system in which this type of‘per pipe’ localisation or addressing is used.

In the example of FIG. 7 the multi-pipe air sampling system may feedinto a single contaminant detector such that it requires sampling of onepipe at a time, in order to determine which of the pipes has thecontaminant in the air stream. This can be achieved by sealing all butone of the pipes and allowing a sample to enter the detector from onepipe at a time while the detector measures the contaminant level. Thisis repeated for each of the pipes in the multi-pipe air samplingnetwork. The sealed pipe must be fully sealed against air flow in orderto obtain accurate measures of the contaminant level in the open pipe.However, complete sealing is very difficult to achieve in low orreasonable cost valves. However by using a method similar to thatdescribed in connection FIGS. 8, 9A and 9B the requirement of completesealing can be avoided.

FIG. 10A schematically illustrates a sensing system 1010 having and asampling pipe network 1011 comprised of a total of two sampling pipes1012, 1014. Each sampling pipe 1012, 1014 defines an air intake paththerethrough. The air intake paths are combined at manifold 1016. Themanifold 1016 may include suitable baffles to assist with combining theair flows. Air is drawn through the sensing system 1010 through the useof the fan 1018. A subsample from the combined air flows is drawnthrough detector loop 1020 in which a filter 1022 and a particledetector 1024 are provided. Once the air flow has passed throughdetector loop 1020, it rejoins the main air flow path 1019. A flowsensor 1026 may optionally be provided prior to the outlet 1028 of thesystem 1010. As will be appreciated the sensing system 1010 isequivalent to the detector 11 of FIG. 1.

Each of the sampling pipes 1012, 1014 has a valve such as a butterflyvalve or another type of flow modifier 1030, 1032. Additionally, eachsampling pipe 1012, 1014 includes an ultrasonic flow sensor 1013 and1015.

It should be noted that, although the valves 1030, 1032, flow sensors1013, 1015 and manifold 1016 are illustrated as forming part of thesampling network 1011, they may equally be physically located within thehousing of the sensing system 1010 and thus form part of the sensingsystem 1010 without changing operation of the present invention.

A method according to the present invention will now be described inconnection with FIGS. 10B to 10D. In normal operation, each valve 1030,1032 is fully open as shown in FIG. 10B. However, when the particledetector 1024 detects the presence of a contaminant in the sampled airflows at a predetermined level, the scanning method according to thepresent invention is undertaken. Firstly, the first sampling pipe 1012is partially closed as shown in FIG. 10C. In this condition, theparticle detector 1024 takes a measure of the contaminant (C₁).Additionally, the flow rate is measured in the sampling pipes 1012, 1014(F_(mp), where F is the flow, m is the measurement number and p is thepipe number. Thus, the flow rate measurements will be F₁₁ and F₁₂) withflow sensors 1013 and 1015 respectively.

In the next step, the other sampling pipe 14 is partially blocked bymoving the butterfly valve to the position illustrated in FIG. 10D. Inthis condition, the particle detector measures the contaminant level(C₂). Additionally, flow rate measurements are taken (F₂₁, F₂₂).

Assuming that the amount of contaminant (or relative amount ofcontaminant between pipes) is not changing significantly during thescanning period, the individual contaminant measurement for a pipe canbe calculated from the following set of simultaneous equations:C ₁ =X ₁ F ₁₁/(F ₁₁ +F ₁₂)+X ₂ F ₁₂/(F ₁₁ +F ₁₂)C ₂ =X ₁ F ₂₁/(F ₂₁ +F ₂₂)+X ₂ F ₂₂/(F ₂₁ +F ₂₂)

-   -   where X₁ is the actual contamination in pipe 1 and X₂ is the        actual contamination in pipe 2.

Advantageously, embodiments of the present invention enable cross-talkbetween the sample pipes, caused by imperfect sealing of the samplepipes, for a given species of contaminant to be eliminated withoutcostly, precision valving. Instead, low-cost butterfly valves or othertypes of flow modifiers are sufficient to accurately eliminate thecross-talk, and allow pipe addressability to be achieved.

As noted above, the instead of using valves to partially close thepipes, a filter could be selectively interposed into the pipes to reducethe contaminant level in each pipe temporarily by a known amount(preferably to 0) and the method adjusted to solve for Contaminant levelas described above for hole addressing.

In the various embodiments described herein, a common step which isperformed, is an initial detection of particles at a detector and moreparticularly an attempt to accurately identify the receipt of the smokefrom a particular sampling inlet of the sampling system. In particular,the event which is most commonly sought to be detected is an arrival ofa smoke front that is propagating down sampling pipe, and whichrepresents smoke which entered a particular sample inlet after a changein the operation in the sample network, e.g. opening or closing ofvalves or flushing the pipe network with clean fluid, or reversing flowdirection or the like. FIGS. 11A and 11B illustrate this concept.

FIG. 11A illustrates a particle detection system 1100, which includesthe detector 1102, and a sampling pipe network 1104. Sampling network1104 has three sample inlets, 1106, 1108 and 1110. A smoke plume 1112 islocated adjacent to sampling inlet 1108. Take for example a situation inwhich the direction of flow in the sampling network 1104 is reversed andthe detector 1102 is attempting to determine the time of arrival ofsmoke entering the system from sampling hole 1108. A graph of determinedsmoke concentration against time is illustrated in FIG. 11B. Initially,for some period, 1020 low smoke level is detected as the sample fluidarriving at the detector only contains sample fluid from sample inlet1106. At time T1, an increase in smoke is detected. Over the next timeperiod 1022, when the sample from inlet 1108 begins arriving thedetected smoke level ramps up until time T2, when approximate steadystate level is detected. In the graph of FIG. 11B, the ramp-up 1022 isnot due to an increase in smoke level, but due to a smearing ordiffusion of the smoke front of sample entering sampling hole 1108. Ifthe entry of particles from the environment into the sampling networkwas even and instantaneous, there would be a step change in the smokelevel detected by the detector 1102, at T1 when the sample from hole1108 arrives at the detector 11.

The present inventors believe that there are a range of factorscontributing to the diffusion of the smoke front, representing thearrival of the sample portion that includes an air sample drawn througha particular one of the sample inlets of the sampling system. Chiefamongst these is suspected to be the existence of a flow speed gradientacross the cross-section of the air sampling duct. FIG. 11C illustratesa cross section through an air sampling duct 1130 such as pipe 1104.Arrows 1132 indicate that flow rate in the central portion of the duct1130 is greater than the flow rate near the walls of the duct.

The belief is that it takes some amount of time for a sample being drawnin through a sample inlet, e.g. 1134 to break into the fast flowingcentral region of the flow in the duct 1130, and therefore the smokefront is smeared out when it arrives at the detector. This mechanismhowever has competing factors, namely initially a sample will beintroduced into the slow flowing peripheral air within the duct whichwill delay its arrival at the detector. However over time part of thesample will find its way into the fast flowing central region which willminimise its transport time to the detector.

The inventors have proposed that a physical structure can be placed inthe duct of the sampling network (i.e. in the pipe of the samplingnetwork) to ameliorate this problem. In a first family of solutions, theinventors propose a sample injection inlet which extends inward from thewall 1131 of the pipe 1130, towards the centre 1133 of the pipe 1130, soas to deliver the sample in the faster flowing region of the sampleflow. Three examples of such a sample injection inlet are shown in FIG.12.

In FIG. 12, a duct forming part of an air sampling system in the form ofpipe 1200 is illustrated. The pipe 1200 is defined by a wall 1202. Threesample injection inlets 1204, 1206 and 1208 are also illustrated. Thefirst sample injection inlet 1204 is a short tube 1210, which extendsfrom the side wall into the pipe 1200, towards its centre 12-12. Sampleinjection inlet 1206, is similar to inlet 1210 but terminates on itsinside end 1214 with a Chamfered tip. The tip has the effect offunctionally making the outlet 1216 point in a downstream direction withrespect to the flow within the pipe.

Finally, sample injection inlet 1208 takes the form of an inverted Lshaped tube 1220. Its inlet is external to the duct 1200, and its outlet1222 faces in a downstream direction and is aligned with the centre ofthe duct 1200, thus injecting samples, drawn into the sample inlet 1208,at the centre of the pipe in the fastest flowing fluid flow. These threeexamples take advantage of the faster flowing central region of flowwithin the pipe to minimise smearing of samples drawn in through thesample inlet.

An alternative to this injection method is illustrated in 13A to 13D.This series of examples uses a structure which creates turbulence withinthe duct of the sampling system to prevent or disrupt laminar airflowwithin the sampling duct, to thereby minimise flow gradient of the typeillustrated in FIG. 11C. FIGS. 13A to 13D each illustrate a segment ofduct 1300, 1310, 13,20 and 1330 respectively.

In FIG. 13A, the inside wall 1302 of the duct 1300 is used as aturbulator. The wall 1302 has been roughened or given surface contour ortexture such as ribs, lines, bosses, or other, to create a rough surfacethat disrupts flow across it.

In FIG. 13B the turbulator is a series of turbulence causing protrusions1312 extending inward from the wall 1310 of the pipe, and are used tocaused disruption of laminar flow within the pipe 1310.

FIG. 13C illustrates an example in which a plurality of turbulencecausing members extend the full breadth of the pipe 1320. In thisexample the turbulators are in the form of open mesh elements 1322. Theopen mesh elements 1322 have a hole size sufficiently large that theywill tend not to clog over time but will cause turbulence to be createdin the pipe 1320. As will be appreciated by those skilled in the art, arange of different shaped turbulators which span across the interior ofa sampling duct can be devised.

FIG. 13D illustrates a further example in which a moving turbulencecausing element 1332 is placed inside the pipe 1330. In this case, aseries of fans 1334 and 1336 are supported in the pipe 1330. The fansmay be actively driven or passively rotating, but serve to stir the airor cause turbulence therein, as the air flows past them.

In this example, it has been convenient to describe the turbulencecausing structure in a region of the duct which is an adjacent samplinginlet, however it should be noted that there is no particular reason whythis should be done and the turbulence causing structure could be placedaway from sampling inlets.

As will be appreciated with the four examples described above, thepurpose of the turbulence causing structure is to break down the flowprofile across the air sampling duct such that the air entering from asampling inlet will travel along the sampling duct to the detector likea ‘packet’, rather than having part of it travel relatively faster orslower than another part and thereby smear out the arrival of the samplefront at the detector.

Alternatively, or in addition to the techniques described above, thepresent inventors have identified that additional improvements indetecting which sample inlet of a plurality of sample inlets, smoke isreceived from by at least partially ameliorating the effect of dilutionon air samples drawn into the sampling network. Consider a particledetection system such as that illustrated in FIG. 11A. In such a system,the air sample drawn into sampling pipe 1108 will be drawn into thesampling pipe 1104, where it mixes with, and is diluted by a sampledrawn from sampling point 1110. Similarly, the air sample drawn fromsample inlet 1106 is diluted by samples drawn from all up-stream sampleinlets. Thus, by the time air samples arrive at the detector 1102, theactual concentration of particles which is detected will be greatlydiluted compared to the sample concentration in the atmospheresurrounding the particular sampling inlet through which the particlesentered the sampling network. The present inventors have determined thatcertain modifications to the systems described herein can be performedto ameliorate this problem, either by increasing the concentration ofsamples drawn into the sampling pipe, such that they more closelyreflect the actual concentration of particles in the atmospheresurrounding this sampling point and/or by providing mechanisms fordelivering samples to the detector with minimal additional dilution.

FIG. 14 illustrates a first exemplary system 1400 which implements sucha technique. The system 1400 includes a detector 11, and an air samplingnetwork 26 including a sampling pipe 28 having five sample inlets 29 atthe far end 1402 of the air sampling pipe 28, the detector system 1400includes a sample amplification arrangement in the form of bellows 1404,which are driven by an actuation means 1406. The bellows 1404 performthe function of blowing or sucking air along or from the sampling pipenetwork in a manner to be described below. As will be appreciated bythose skilled in the art, a wide variety of systems could be used toreplace the bellows structure, for example, a reciprocating pneumaticpiston, or reversible fan or pump or other like air movement devicecould be used in place of the bellows 1404.

Operation of system 1400 will now be described. Initially, onceparticles at a threshold level have been detected by the detector 11,the system 1400 enters a localisation mode in which the location ofparticles in the system will be determined. In this mode, the primaryair movement system, e.g. the aspirator 16 of the detector 11 is stoppedand the system enters a sample amplification phase in which thecontroller communicates via communications channel 1408 with theactuation device 1406 of the bellows 1404. With the fan stopped, oralternatively with a valve at the detector end of the sampling network26 closed, the sampling pipe 28 contains a fixed volume of air, in usethe bellows 1404 is used to increase and decrease the volume of aircontained within the sampling pipe network 26. When the bellows isexpanded the volume increases and additional sample fluid is drawn intoeach of the sampling inlets 29. When the bellows is contracted someportion of the air within the sampling network 26 is expelled from thesampling inlets 29. By expanding and contracting the volume of airwithin the sampling pipe network, air is repeatedly pumped into and outof each of the sampling inlets creating a localised sample portionwithin the sampling pipe 28, surrounding each of the sampling inlets 29,which more closely reflect the level of particles of interest in theenvironment directly adjacent each of the sampling inlets 29, than wouldbe the case with the continually drawn and continually diluted samplestream.

Consider the situation at a single one of the sampling inlets 29, theair sample drawn into the sampling inlet enters the sample pipe networkand mixes with the existing flow within the pipe 28. The existing airflowing past the sampling inlet dilutes the sample with samples drawnfrom all upstream sampling inlets. When the flow in the pipe 28 isstopped by closing a valve 1410 at the detector end of the pipe 28 orpossibly by stopping the aspirator of the detector 11, then the bellows1404 are contracted and then, some portion of air within the samplingpipe 28 surrounding the sampling point 29 is expelled from the samplingpoint 29, as air is pushed along the sampling pipe 29 by the bellows.However, the air which is expelled from each sampling point includes thediluting samples from the upstream sampling points. Suction is againapplied to the pipe network 28 by expanding the bellows 1404 and anadditional air sample is drawn into each sampling point. Whilst thissample is also diluted by the fluid which already exists within thesampling pipe adjacent the sampling point, part of this diluting air isthe air sample which was previously drawn into the sampling point ofinterest. Therefore, the total concentration after the second samplingis increased compared to the first. With repeated cycles of expellingand sampling via a sampling inlet, the proportion of air within the pipe28 in a portion of the sample surrounding the sampling inlet begins toapproach increases and the particle level begins to approach that in theatmosphere surrounding sampling inlet. Using this method, discretesample portions within the sampling pipe 29 are formed which represent,more closely, the environment surrounding the sampling inlets. Becausedilution is reduced, the methods described above which rely on detectionof the onset of a smoke level increase i.e. a smoke front to determinethe location of entry of particles along the sampling network can beimproved. Once the sample amplification phase is completed the systementers a transportation phase and moves the sampled air, now includingsample packets which are relatively localised, back to the detector foranalysis.

FIGS. 14A to 14E illustrate an exemplary system that uses a vibratingmembrane, e.g. a speaker to perform sample amplification. The system1420 includes a particle detector 11 coupled to an air sampling network26. The air sampling network 26 includes a sampling pipe 28 having aplurality of air sample inlets 29. The air sampling network is coupledto the detector via a sample amplification arrangement 1422 andaspirator 1424. The aspirator 1424 operates to draw samples into thesampling network and push them to the detector 11 for analysis in amanner that will be described in more detail bellow. The sampleamplification arrangement 1422 performs a similar job to the bellows ofFIG. 14 in that it causes oscillation of the flow direction in the airsample system to promote mixing of air in the region of surrounding eachsample inlet 29 and air in the sampling pipe 28. In this example thesample amplification arrangement 1422 includes a membrane 1426 that ismounted within a housing 1428 and driven back and forth in reciprocatingmotion by an actuator. The actuator and membrane can be provided by aloudspeaker. Preferably the membrane is made to oscillate at a subsonicfrequency, and most preferably at between 2 and 10 Hz.

In ordinary operation the aspirator 1424 runs at a first speed settingthat is sufficient meet sample transport time requirements and draws airsamples to the detector 11. Once particles are detected in the sampleflow, the system 1420 enters a localisation mode beginning with a sampleamplification phase. In this phase, illustrated in FIG. 14A, the fanenters a low speed operation and the sample amplification arrangement1422 is activated. The membrane 1426 oscillates and agitates the air inthe pipe 28 to cause mixing with air nearby the entrance to each sampleinlet 29. Because the fan is running at low speed, a mixed air samplethat more closely approaches the true particle concentration in the airsurrounding the sampling network 26 enters each sampling inlet 29 andslowly builds a packet of air downstream of each inlet. In FIGS. 14B to14D the agitation is continued as the fan 1424 runs slowly and buildsthe sample packet 1430.

Next in FIG. 14E, the system 10 enters transportation phase. In thismode the fan 1424 increases speed, and the membrane 1426 is stopped. Thesample packets, e.g. 1430 are then drawn back to the detector 12 withthe fan running in fast mode. As described below, various techniques(e.g. by blocking sampling inlets, opening the end of the pipe etc.) canbe employed to minimise mixing or smearing of the sample packets tothereby increase the reliability the localisation techniques applied.FIG. 15 illustrates a second embodiment of a system 1500 which performsa similar method to that described in connection to FIG. 14.

In FIG. 15 like features have been like numbered with respect to FIG. 14and the earlier embodiments and for brevity will not be re-explained. Inthis example, the sampling network 26, at its distal end 1502 includes afan 1504, and a valve 1506. Optionally at the end 1508 of the samplingpipe 28 which is closest to the detector 11, there may additionally be asecond valve 1510. In this example, the valve 1506 is normally closedwhile valve 1510 is open during ordinary operation of the detector 11.Once the detector goes into its localisation mode however, the positionof the valves 1510 and 1506 is changed and valve 1510 is closed andvalve 1506 is opened. The fan 1504 is then used to perform the samefunction as the bellows 1404 of FIG. 14. In this regard the fan 1504 isused to either blow some of the contents of the sampling pipe 26 fromthe sampling points 29, or suck samples in through the sampling points29 as described above. As will be appreciated, this oscillation ofbetween sucking and blowing samples can be performed by the primaryaspirator of the particle detector 11. However, by putting the fan 1504at the far end of the sampling pipe network 28, an additional advantagecan be gained, namely that the fan 1504 can be used at the end of thisprocess to push the contents of the sampling pipe 126 to the detector11, rather than using the aspirator of the detector 11 to suck airsamples down the sampling pipe 28. The advantage of using a blower fan1504 at the end of the pipe 28 is that the sampling pipe 28 becomespositively pressurised and thus during the transportation phase does notdraw any additional air samples from the environment surrounding thesampling points 29. In this way, a relatively undiluted column ofsampling air containing packets/portions of sample air corresponding toeach sampling inlet 29 is delivered to the detector 11 such that the‘packets’ of sample which were formed by the oscillation process can bedistinctly detected by the detector 11. As will be further appreciatedthe oscillation of between sucking and blowing samples during sampleamplification can be performed by using the primary aspirator of theparticle detector 11 and the fan 1504 operating in concert. For example,both fans may be set to operate synchronously, i.e. moving air in onedirection and then the other to enhance localised mixing of samplesaround their respective sampling holes, or alternatively the fans can beset to alternately apply suction to their respective ends of pipe 26 todraw the sample fluid along the pipe in one direction. Thus rather thanusing the bellow-like push/pull on the sample flow from one end of thepipe 26 an alternating pull/pull mechanism from two ends of the pipe isused. At the non-pulling end a valve can be closed (or partially closed)to control the amount of sample flow entering the pipe's 26 end.Advantageously this mechanism allows the system to increase theconcentrating effect of bellows action. It also allows the sample packetto be formed on both upstream and downstream of the sample inletposition. The increased concentrating effect also enables the system tocut down on the number of flow oscillation cycles for any givenconcentration increase or mixing increase, relative to a system thatacts at one end. This scheme may also average out (and possiblyneutralise) the effect that fires closer to the detector end up with ahigher slug concentration. As will be described below in connection withFIGS. 18 and 19 a double ended flow modulation can be advantageouslyused to selectively perform sample amplification.

The system of FIG. 15 can be further modified as illustrated in FIG.15B. In this example the particle detection system 1350 includes an airsampling system similar to that of FIG. 15 and similar features havebeen like numbered. However this system 1520 additionally includes twobranch pipes 1522 and 1524 which enable additional modes of operation.The first branch 1522 is located at the downstream end of the pipenetwork, ideally between the entry to the detector 11 and the nearestsampling point 29. The branch pipe 1522 includes:

-   -   A fan 1526, which can be used to purge the sampling system in a        manner to be described.    -   A filter 1528, which may inter alia be a HEPA filter or the        like, which is used to clean the purging air delivered by the        fan 1526.    -   A valve 1530 for selectively opening and closing the branch 1522        as needed.

The second branch pipe 1524 includes a valve 1532, and is used as anexhaust from the sampling pipe 28 during purging, as will be describedbelow.

The system 1520 operates the in the same way as the system 1500 of FIG.15 in detection mode, namely with the main aspirator of the detector 11acting to draw air samples through the sampling inlets 29, along thesampling pipe 28 to the detector 11 for analysis. In detection mode thevalves 1530, 1532 and 1502 are closed to prevent the air which is notassociated with a sampling inlet 29 from being drawn into the system anddiluting the air samples. Valves 1510 is open.

Once particles are detected to a sufficient extent, the system 1520 goesinto localisation mode and the following steps occur:

-   -   Valve 1510 is closed and the fan of the main detector 11 stops        drawing air down the sampling pipe 28.    -   Valves 1530 and 1532 (and possibly also 1502) are opened to        enable purging of the sample air from the sampling pipe 28.    -   The fan 1526 is activated, and air is drawn into the branch        1522, through the filter 1528, where it is cleaned and into the        sampling pipe 28. This clean air purges the pipe 28 of particle        laden air and displaces it with clean air.

Valves 1530, 1532 and 1502 are closed and valve 1510 is opened and themain detector 11 fan is used to draw new air samples into the samplinginlets 29. This process only operates for a short period of time, saybetween 5 and 20 seconds, or as long as possible so as to avoid mixingof air samples that are drawn into adjacent sampling inlets 29. In thisway packets of particle laden air are built up in the pipe 28. As willbe appreciated this step could be augmented by performing one of thevarious concentrating techniques described herein, but in thisembodiment sufficient sensitivity might be achieved without this addedcomplication. As noted above, the use of the pusher fan 1504 also aidsin delivering a relatively undiluted column of sampling air to thedetector 11, which may obviate the need for an amplification stage insome embodiments.

-   -   The detector then moves into a transportation phase in which the        main detector's 11 aspirator is then deactivated and valve 1502        opened. Valve 1510 remains open.    -   The pusher fan 1504 is activated and the packets of sample air        are pushed down the pipe 28 for analysis.    -   The air samples are then analysed and the presence of particles        versus volume (or other techniques) is used to determine through        which inlet 29, the particles entered the system. In this        example, analysis of the sample air in the localisation phase is        performed by second particle detector 1534. This detector has a        relatively fast response compared to that of detector 11.

This detector 1534 may not be as sensitive or stable in its output asdetector 11, but as the particle level is likely to have increased (e.g.because of an increase in fire activity) as the localisation process istaking place, speed of detection may be a priority over sensitivity oraccuracy. Furthermore actual particle concentration data can still beobtained by the main particle detector 11 as the air samples can passthrough both detectors in series.

The main detector 11 and high speed detector 1534 may be part of thesame particle detector (e.g. two particle detection chambers in a singledevice) or may be different devices, e.g. located in series. Furthermorethe main detector 11 may be used alone. In this case the main detectorcould optionally be configured to operate in a high speed mode in whichit has an improved response rate compared to its ordinary detectionmode. This could be achieved by temporarily changing software parametersof the detector 11 e.g. reducing periods over which particleconcentration levels are averaged etc. or by activating a second dataprocessing path which receives detection chamber output data (orsimilar) and which is optimised for response rate.

As will be apparent from the foregoing the branches 1522 and 1524 andtheir respective components, and the fast response detector 1534, areoptional additions to the system 1500 of FIG. 15. In order to implementthe foregoing method all that is really needed over and above the system1500 of FIG. 15 is a mechanism for delivering purging air to the pipenetwork 26 and a mechanism for controlling the system's valves to enterand exit the purge mode.

FIG. 16 illustrates a further example of a system implementing theoscillation method and a mechanism for reduced dilution of delivery offinal, increased concentration, air samples to the detector. The system1600 includes a detector 11, and sampling pipe network 26, as describedin connection with FIGS. 14 and 15, and similar features have beenlabelled with the same reference numerals. In this example, the processof oscillating between sucking and blowing samples is performed by theprimary aspirator of the detector 11. The sampling network 26 isadditionally provided with a valve 1602 located upstream of the finalsampling inlet 29. After sample concentration has been increased, asdescribed above, using the main aspirator of the detector 11, the valve1602, which is coupled to the controller of the detector 11 bycommunications channel 1604, is opened. The valve 1602 is configured toopen the end of the sampling network to the atmosphere such that itapproximates an open pipe which has substantially less flow impedancethan any one of the sampling inlets 29. When the aspirator of thedetector 11 then applies suction to the sampling network 26, drawing airis preferentially drawn into the end of the sampling pipe 28, and thesample packets already within the pipe 28 are drawn along to thedetector 11. Because the open pipe end has low flow impedance, the levelof air drawn into each of the sampling inlets 29 is greatly reduced,thus greatly reducing dilution of the samples as they are delivered tothe detector 11. The reduced tendency for air to be drawn into thesampling inlets 29, when the valve 1602 is opened will also reduce themodification of the sample packets by smoke in the environment at ornear the location of other sampling holes. The reduced flow into thesampling holes 29 when the valve 1602 is open will also make thecalculation of the smoke source position less dependent on the flow atthe sampling holes. As described above, the system is initially trainedto determine which hole a sample packet has arrived from based on howmuch air is drawn through the sampling network once the localisationphase has been entered. However, because the sampling holes may block ina variable way over time the reliability of volume or time measurementsbased on the initial training may vary over time. By opening the valve1602 the sample inlets 29 become less influential in the flow in thesampling pipe 28 and consequently the effect of differential blocking ofthe sampling inlets 29 over system life will be reduced. Finally openingthe valve 1602 will reduce flow impedance and the transportation phasefaster. e.g. 40 sec for a 100 m pipe at 50 L/min rather than 110 secwith the end of the pipe closed.

In some embodiments the valve 1602 of sampling network 28 beyond thelast sampling inlet 29 can be provide with a filter, e.g. a HEPA filterthrough which air is drawn. This assists the sample packet from the lastsample inlet 29 in standing out from the air being drawn into the end ofthe pipe which might also contain particles or interest or even dust.Such a HEPA filter could also be used in conjunction with a pusher fanto implement a purging phase similar to that described in connectionwith FIG. 15B, by suitable operation of the valves 1602 and fans of thesystem.

As will be appreciated in the examples given herein, valves couldadditionally be applied to each of the sampling inlets 29 to furtherfacilitate the effect of the flow control mechanisms (e.g. bellow, fan,valve and equivalent structures) applied to the end of the pipe. Forexample, each of the sampling inlets 29 can be provided with a valvewhich is controlled in concert with the pipe end flow control system tooptimise its performance.

FIGS. 20A and 20B illustrate two embodiments of the present invention,which may offer a particularly convenient set up compared to some of theembodiments illustrated above. These embodiments can be used in a mannerequivalent to the systems of FIGS. 14 and 15 respectively, and likefeatures have been like numbered.

The system 2010 of FIG. 20A differs from the embodiment of FIG. 14 inthat the air sampling pipe 28 is provided with a return portion 2002connected to the upstream end of sampling pipe portion 2012. This bringsthe far end 1402 of the sampling network 26 back to a location near tothe detector 11. In this example, the bellows 1404 and its associatedactuation means 1406 along with valve 1510 are mounted together in acommon module 2004. Most preferably module can be connected mechanicallyand electrically to the detector 11. In a similar fashion, the system2000 of FIG. 20B differs from the embodiment of FIG. 15 in that the airsampling pipe 28 is provided with a return pipe portion 2002 connectedto the upstream end of sampling pipe portion 2012. The far end 1502 ofthe sampling network 26 is thus located near to the detector 11 suchthat the fan 1504 and with valves 1506 and 1510 can be mounted togetherin a common module 2004.

A localisation module (e.g. module 2004) can be used to implement anyembodiments of the present inventions described herein in a convenientmanner. Such modules could be retrofitted to detector systems notoriginally intended to perform localisation or provided as optionaladd-on modules so that purchasers of new equipment can be provided witha choice as to whether or not to buy a detector with these features. Forexample a module could be provided which implements the system of FIG.15B by housing the following equipment:

-   -   the branch 1524 with vales 1532,    -   valve 1506 and pusher fan 1504    -   branch 1522 with its fan 1526, 1528 and valve 1530 along with        valve 1510.

Similarly the valve 1602 and possibly also a HEPA filter could be housedin a similar module.

Whilst these embodiments require an extra length of pipe for the pipenetwork to loop back to near the detector 11, they offer the advantagethat power and electrical communications lines do not need to be run toa position remote from the detector 11 to power and control thecomponents of the system mounted to the upstream end 1402/1502 of thesampling pipe network 26, This may assist in making system installationmore straightforward. Moreover it facilitates commissioning and testingsince the most complex components are now located at a single location.

In the various embodiments illustrated in FIGS. 8, 9 a and 9 b, 14through to 20 b. Various components of the systems described arerequired to communicate with the detector 11 or other control componentof the particle detection system illustrated. In the previouslydescribed embodiments communication takes place usually over a hardwired communications channel, or optionally via a wireless (e.g. radio)communication channel, for example communications link 1408 in FIG. 14).The present inventors have realised that a hard wired communication pathneed not be present but that the airflow path through the detectionsystem could be used for communication between the detector or othercontrolling entity and another component or accessory of the system.

In most embodiments, the accessory will comprise a flow control devicesuch as a valve, fan, filter or other element of the system that takespart in performing localisation technique described herein for examplethe accessory could include the valve 1502 and/or fan 1504 as used inthe example of FIG. 15. Details of an exemplary accessory, in the formof a valve, are illustrated in FIG. 28.

The accessory 2800 is mounted to a portion of a sampling pipe 28 and hasaccess to the airflow path 2802 contained within the sampling pipe 28.The accessory 2800 includes one or more sensors 2804 which are used tosense the condition in the airflow path 2802, such as flow speed,direction and/or pressure. The sensors 2804 are connected to controller2806 and pass output signals indicative of their sensed condition to it.The controller 2806 receives sensor signals and processes these, and inturn controls the operation of the accessory as required.

In the present example the accessory 2800 includes a valve 2808 whichmay be selectively opened and closed under control of the controller2806. The accessory 2800 is preferably powered by a battery 2810, ratherthan by hard wired power connection (although this is possible) in orderto minimise wiring and installation requirements for the accessory.

In use, sensors 2804 are used by the accessory 2800 to sense the presentstate of the primary particle detector by receiving and detectingchanges in airflow in the air sampling pipe 28. The controller 2806interprets changes in the air flow 2802 as a communication from thedetection system, and in response determines what action it should betaking at for the present instant. For example, in the localisationtechniques described herein, the localisation phase may be begun bytemporarily shutting down, slowing or changing direction of the mainaspirator of the detector 11 or by changing the condition of one or morevalves at the detector end of the system. This in turn causes the airflow 2802 in the sampling pipe 28 to change. The variation in air flowis sensed by the sensors 2804 as a changing air flow speed and pressurein the pipe 28. The change is interpreted by the controller 2806 to be acontrol signal from the detector 11 to take an appropriate control stepin response to the sensed change in flow pattern. For example, detectinga cease in airflow 2802 may signal to the controller 2806 that thedetection system has gone into a localisation mode and that the valve2808 should be opened. Alternatively, more complex operations may beperformed upon detection of a control signal through the air flow path2802. For example, when the accessory 2800 senses that the system hadentered localisation mode, the accessory enters its localisation mode inwhich a localisation routine is performed. This may involve theaccessory operating in a first condition for first time period and thenin second condition for a second time period and so on. To give a moreconcrete example, the valve 2802 may be controlled to remain closed fora predetermined period of time, say one minute while the other elementsof the particle detection system perform a sample amplification routine.After the predetermined time elapses the controller may cause the valve2808 to open in order for the detector to operate in a “transportationphase” of the localisation process to enable the delivery ofconcentrated sample “packets” back to the detector 11 for analysis.

As would be appreciated, if the localisation process includes anoscillation in flow in order to perform sample amplification, thesensors 2804 can sense the oscillation and the controller can respond tothis to ensure that the valve or other flow control structure of thelike is set in its appropriate operating condition.

Patterns of temporal changes in airflow can also be created by thedetection system to encode control messages for an accessory, or toallow addressing of particular accessories in systems with multipleaccessories that require independent control (e.g. the valves 802, 902in FIGS. 8 and 9A)

This principle of operation to be extended to use the air flow pathwithin the air sampling system 26 of a detector system to communicate inother ways such as by the application of sound pulses or the like.Clearly in such embodiments sensors in the form of suitable acoustictransducers would be needed in the accessory to sense thesecommunication signals.

FIG. 29 illustrates a particle detection system 2900 including aparticle detector 11, a localisation module 2004 and sampling pipenetwork 26 and an accessory 2902 similar to that described in connectionwith FIG. 28. The sampling pipe network 26 includes a sampling pipe 28having a series of sampling inlets 29 spaced along its length. Thelocalisation module includes 2004 includes a reciprocating piston 2904which acts as a sample amplification arrangement in the localisationprocess.

The accessory 2900 in this example includes a fan 2908 and a valve 2910which are controlled by a controller of the accessory in response to theaccessory's sensors (being a flow sensor and pressure sensor, that arenot shown) detecting signals in the sampling pipe 28 that indicate thestate of the system.

In ordinary detection mode the accessory has its valve 2910 closed sothat samples are drawn through the sample inlets 29. When the detector11 detects particles at a predetermined level it enters a localisationmode. This initially involves a purge phase in which the main aspiratoris reversed and air blown out of the sampling pipe 28. This causes anincrease in pressure in the (previously slightly negatively pressurised)sampling pipe. The sensors of the accessory 2900 detect this and itinterpreted by the accessory's controller as a signal that localisationmode has been activated. The controller then opens the valve and allowsair to be purged out through the end of the pipe 28 to atmosphereinstead of out through the sample inlets.

When this flow ceases the reduction in pipe pressure and flow isdetected by the sensors of the accessory 2900 and the processorinterprets this as a signal to close the valve 2910.

Next the localisation module 2004 performs sample amplification by usingthe piston to oscillate the sample flow in the sampling pipe in a mannerdescribed above. The sensors of the accessory 2900 and detect theoscillations in flow and/or pressure and the processor interprets thisas a signal to keep the valve 2910 in the closed position while sampleamplification occurs.

Upon detecting ceasing of the oscillation phase, the accessory 2900interprets this as an instruction that the transportation phase hasbegun and opens its valve 2910 and activates its pusher fan 2908 to pushthe sample to the detector 11 for analysis.

The transportation phase is stopped upon the accessory 2900 sensing achange flow caused by the detector or localisation module. For example,the main aspirator of the detector 11 could be temporarily stopped,slowed or reversed, a valve closed, to cause a pressure change thatsignals the end of the transportation phase to the accessory 2900. Inembodiments with a pusher fan 2908 such as this one, the transportationphase could be run for a predetermined time if running the pusher fanmakes receiving a signal from the detector via the airflow pathunreliable.

At the end of the transportation phase the accessory closes the valve2910 and the system returns to normal detection operation.

FIG. 21 illustrates a further embodiment of an aspect of the presentinvention that leverages the existence of a pair of side by side pipeportions provided in embodiments like that of FIGS. 20A and 20B. Theparticle detection system 2100 is similar to the system of FIGS. 20 and20A, however the positioning of the sample inlets along the pipe network26 have been adjusted to aid the process of localisation. In this regardone of the difficulties in a practical implementation of thelocalisation techniques described herein is that of the ability toresolve neighbouring addresses, i.e. if the sample inlets join asampling pipe too close together, it can be very difficult to detectwhen an air sample from one sampling inlet ends and an air sample fromthe next sample inlet begins. In the present embodiment, and that ofFIGS. 22 and 23, the ability to resolve samples has been enhanced byarranging the position of the sampling inlets along the sampling pointssuch that they are spaced out further than the minimum spacing. Turningnow to FIG. 21 which illustrates a particle detection system 2100including a particle detector 11, a localisation module 2004 andsampling pipe network 26. The sampling pipe network includes a samplingpipe 28 having a series of sampling inlets 29 spaced along its length.Similar to FIGS. 20A and 20A, the sampling pipe is a loop arrangement,or rather has two pipe portions following a similar path, e.g. two pipes28A and 28B running parallel or generally in a side by side arrangement.However in contrast to the embodiment of FIGS. 20A and 20B the samplinginlets 29 in the system 2100 are spaced along both pipes portions 28Aand 28B, thus the upstream pipe 28B is not provided to simply allowconvenient connection of the upstream end of pipe particle portion 28Ato the localisation module 2004. Instead, some of the sampling inlets 29are positioned along the upstream pipe portion 28B and others on thedownstream pipe portion 28A. This enables the spacing between samplinginlets to be increased by interleaving sampling points 29 positionedalong the upstream pipe portion 28B with those positioned on thedownstream pipe portion 28A as the sampling pipe 28 traversesneighbouring regions R1 to R8. As will be appreciated, in someembodiments the sampling pipe 28 extends through the regions R1 to R8being monitored and the sampling inlets may be directly coupled to thesampling pipes or even be a hole directly formed in the pipe wall,however, a sampling pipe 28 does not need to actually pass through theregions R1 to R8 in order to service the region. In fact in manyinstallations a sampling pipe will pass by the region but just outsideit, e.g. above a ceiling panel of a room being monitored for particles,outside a housing of a series of cabinets being monitored or the like.These installations may use a length of pipe connected to the mainsampling pipe which leads to a sampling point arrangement that is influid communication with the region being monitored.

In embodiments of this aspect of the present invention, the spacing ofthe sampling point arrangements of neighbouring regions is closertogether than the distance between their points of connection to thesampling pipe network when measured along the flow path in the pipe.

FIGS. 22 and 23 illustrate additional implementations. FIG. 23illustrates a system 2300 including a particle detector 11 connected toan air sampling network 26. The air sampling network includes a singlerun of three side-by-side, preferably parallel sampling pipe portions2202, 2204, 2206. The downstream pipe portion 2202 is connected to theparticle detector 11 on one end and to the next sampling pipe portion2204 on its other end. The sampling pipe portion 2204 is also connectedto the upstream sampling pipe portion 2206. The sampling points 29 arearranged such that each sampling point 29 connects to a differentsampling pipe portion to its neighbours. That is, the sampling pointservicing R1 connects to pipe portion 2202, whereas the sampling pointservicing R2 connects to sampling pipe portion 2204, and the samplingpoint servicing R3 is connected to sampling pipe portion 2206. Thispattern is repeated such that the sampling point servicing R4 connectsto sampling pipe portion 2202 etc. In this way the distance between thesampling points 29, when measured along the length of the flow path ofthe sampling pipe is three times what is would be if a single runsampling pipe is used. The added separation between the points ofconnection makes resolving samples that are drawn from one samplinginlet from another more straightforward.

A further advantage that may be realised, in addition to the spreadingout of the sampling points along the pipe network, arises from the(relative) re-ordering of the connection order to the pipe network,which it may increase reliability of localisation. In some cases themixing or merging of samples in the sampling pipe network may mask (orfalsely suggest) the presence of particles in physically neighbouringregions. By separating the points of connection of the air samplingpoints of one region, from that of its neighbours, in the sampling pipenetwork (most preferably by connecting a sampling point servicing atleast one non-neighbouring region between them) the level independenceof the air samples within the sampling system may be maintained to ahigher degree.

Accordingly there is provided an air sampling system for a particledetection system for monitoring a plurality of regions, said regionsbeing arranged such that at least one region physically neighboursanother of the regions, wherein the air sampling system includes asampling pipe network including a plurality of sample inletarrangements, each of which services a respective region, and which isconnected to the sampling pipe such that the sampling inlet arrangementof at least one region has a point of connection that is separated fromthe point of connection of a physically neighbouring region. Mostpreferably the point of connection of a sampling point arrangement of atleast one non-neighbouring region is located between the points ofconnection of sampling inlet arrangements of the neighbouring regions. Aparticle detection system, including the air sampling system and atleast one particle detector is also provided.

FIG. 23 illustrates another embodiment which implements this scheme. Inthis example the particle detector 11 is coupled to a localisationmodule 2004 and sampling pipe network 26. The sampling pipe network 26includes a single sampling pipe 28 having four air sampling pipeportions 2302, 2304, 2306, 2308 connected to each other and co-extendingpast (or through) the regions R1 to R8. In this example, the farupstream end of the pipe 28 connects to the localisation module 2004 asdescribed above. The downstream end of the pipe 28 connects to thedetector 11, via the localisation module 2004. Localization can beperformed using any of the methods described herein.

The sampling inlets of each region R1 to R8 are connected to the pipesegment 2302 to 2308 as follows:

Region R1 R2 R3 R4 R5 R6 R7 R8 Pipe 2302 2304 2308 2306 2302 2306 23042308 segment

Thus the regions are connected to the pipe network from downstream toupstream (i.e. the end nearest the detector to the end farthest from thedetector) in the following order:

-   -   R1, R5, R7, R2, R4, R6, R8, R3

In this way no region has its air sampling arrangement 29 connected tothe sampling pipe 28 next to a neighbouring region, and the points ofconnection are widely spaced along the pipe network.

In all other respects this embodiment can operate in accordance with theother schemes described herein.

The pipe portions may be individual lengths of pipe interconnected withfittings at their ends as will be known to those skilled in the art, oralternatively special purpose multi channel pipes can be used. Theinterconnections of pipe segments then takes place using interconnectionfittings e.g. that may be attached over or into the ends of the channelsof the pipe. The use of multi channel pipes can offer an installationadvantage in that the installation technician need only handle a singleelement instead of multiple pipes.

Whilst the present example has been described with reference to a groupof regions R1 to R8 that are arranged in a straight line, there is noreason that this need be the case. In reality the regions may bearranged in any geometry. Moreover there is no requirement that theregions need to be physically separated, e.g. as rooms are, but may beregions within one larger space or volume.

In order for the above techniques to work reliably in the field, it isnecessary to calibrate or train the system e.g. to as to the volume ofair moved before an air sample entering each sampling inlet arrives atthe detector (or each detector), thus effectively characterising thesystem. Most preferably the system is trained while the air is beingmoved through the system in the same way as during the system'slocalisation mode. For example, if the system uses a pusher fan method,described below in connection with FIG. 15, a significant localisationerror is likely to occur if the system is trained using normal detectionoperation when the pusher fan is not running. In one form, in which thesystem has a single air moving device, e.g. fan or the like or there isno mechanism to dramatically change the flow impedance or flow paththrough the detection system when changing from the detection mode tolocalisation mode, a relatively simple, but time consuming process canbe implemented in training mode. In this case the system can be trainedas follows. With the system operating normally, the system measures thevolume of air moved starting from the time at which a test smoke e.g.smoke spray is dispensed, until the smoke arrives at the detector. Thismeasurement is made for each sampling inlet. However this is can be timeconsuming as the training sequence needs to be performed for each inletseparately and the system may need to be left to return to normaloperation between each cycle. Preferably the training mode uses amodified behaviour to reduce training time.

In other embodiments, e.g. a system which has an open valve plus afilter at end of the pipe during its transportation phase, the trainingmode involves opening the valve at the end of the pipe for a period oftime. Smoke can then be selectively administered to each sample hole (orto multiple holes in selected patterns) so that the system will stillsuck smoke through the holes.

In training mode the system operates as follows:

-   -   a. The system then opens valve at the end of the pipe.    -   b. User then inputs to the detector when smoke is administered        at a sampling inlet.    -   c. The detector measures the volume of air moved starting from        the indicated time until smoke is detected for each sample        inlet.

In embodiments with a pusher fan (and preferably a valve and filter atthe end of the pipe) it is more difficult to simulate smoke entering asampling pipe. For example, it is not possible to get spray smoke into asampling inlet with the pusher fan continuously running. Therefore analternative method is needed. Such as:

a. Replicate the standard bellows operation, but with introduced smoke,including:

-   -   i. Run the system normally;    -   ii. Enter the calibration process;    -   iii. Activate the bellows as if particles had been detected, and        indicate to a user that this process has begun;    -   iv. User applies spray smoke at the sampling inlet under test.    -   v. Deactivate the bellows and turn on the pusher fan to go into        the transportation phase as normal, and record the volume of air        transported before the smoke arrives at the detector.    -   vi. System indicates that the hole has been calibrated.    -   vii. System closes valve and turns off pusher fan.    -   viii. Other sample inlets are then calibrated in the same way.

b. A Special training mode:

-   -   i. System running normally.    -   ii. User puts the system into the test mode.    -   iii. The system continues to draw air in normally and the user        applies spray smoke at hole and indicates this to the system.    -   iv. The system then immediately turns on pusher fan.    -   v. The system then records volume of air through flow sensor        between indication of “spray start” and smoke being detected.    -   vi. The system then indicates that a sample inlet has been        calibrated.    -   vii. System closes valve and turns off pusher fan.    -   viii. The next hole is then calibrated using the same process.

c. Special smoke injector.

This method is faster for the user but the user needs special equipment.This method involves use of an injection device which allows smoke to besprayed into a sample inlet in a manner that other positive pressure inthe pipe. One way of doing this involves use of a test smoke generatorunit that seals around the sample inlet and sprays smoke into the inlet.For example the smoke generator can have an outlet that includes a foamgasket which clamps around the sample inlet so air is not coming out thesample hole. Once fitted and a sample is injected into the samplinginlet the user inputs to the system that this smoke was sprayed. Thesystem records the volume of air moved before the smoke pulse arrives atthe detector. FIG. 27 shows an example device. Although this deviceincludes adaptations that can advantageously be used with videoverification systems, this device may be used without these adaptationsif needed.

Rather than empirically testing the behaviour of the system a simulatorcan be used. The simulator is similar to Aspire (from Xtralis Pty Ltd).The simulator works out the expected volumes per hole during thetransportation phase based on the actual system hole dimensions anddistances.

In the above testing methods a user can either interact with thedetector directly to communicate inputs to it, e.g. to enter trainingmode, or indicate when test smoke has been sprayed etc. However in apreferred embodiment the detector system includes an interface,preferably wireless, by which the detector communicates with a userdevice, e.g. a portable computer, tablet computer, smart-phone or thelike, and the user device runs an application that allows the detectorto be controlled to operate as described.

In some particle detection systems, an enhancement can be provided byinterfacing the particle detection system with a video security orsurveillance system. Such systems use the images captured by the videosecurity system either to perform additional particle detection methods(e.g. by performing video analytics to attempt to verify the detectionof particles) or to allow a human operator of a monitoring station (CMS)to view an area in which particles have been detected so as to havehuman verification of the particle detection event. This may aid indetermining threat level and determining an appropriate response to thedetection event. An example system including a particle (in particularsmoke) detector and video security system is illustrated in FIG. 24.Further details of such systems and their operation are described in theApplicant's co-pending PCT application filed on 7 Jun. 2013 and entitledMulti-Mode Detection.

FIG. 24 is a floor plan of a building 2400 including plurality of rooms.Each of the rooms is indicated as belonging to a zone which is monitoredby a respective camera. In this regard, zone 1 is monitored by camera2401; zone 2 by camera 2402; zone 3 by camera 2403; zone 4 by camera2404; zone 5 by camera 2405; zone 6 by camera 2406; zone 7 by camera2407; and zone n by camera 2408.

Each of the zones also includes a means for detecting particles 2410.1to 2410.n. means for detecting particles 2410.1 to 2410.n could be ofany type, including point detectors, aspirated detectors, beamdetectors, open area active video detectors. In the present example themeans for detecting particles 2410.1 to 2410.n is an air sampling inletto an air sampling pipe 2413 that is connected to a particle detector2411 thus forming a particle detection system of any one of the typesdescribed herein. The particle detection system is arranged to determinewhich sampling point 2410.1 to 2410.n particles entered, as describedherein and indicates a particle level or alarm level for each detectorpoint 2410.1 to 2410.n. The particle detector 2411 connected to samplingpoints 2410.1 through 2410.n and is connected to a building fire alarmsystem either in the form of an FACP or central controller 2412, andarranged to individually identify each sampling point as having anaddress on that system to enable the location of fire detection withinthe building 2400 to be indicated by the fire alarm system. Each of thecameras 2401 to 2408 are connected to a central control system 2412. Thecentral control system 2412 is a video analytics system which receivesand analyses video feeds from the multiple cameras. The centralcontroller can also store and transmit video feeds to a centralmonitoring station either in real time or on demand as events aredetected. The controller 2412 is connected via a communications channelto a central monitoring station (CMS) 2414, at which alarm situations,both fire related and security related, can be monitored. In alternativeembodiments the functions of the controller 2412 and FACP can becombined into a single device. Also the functions of the centralmonitoring station 2414 could be performed at the controller 2412.Similarly the cameras and other security systems (not shown) and fireand/or smoke can connect directly to a remote CMS which performs allmonitoring and analysis (i.e. the functions of the controller 2412 andFACP) directly.

Consider now a situation in which a fire starts in zone 2 of thebuilding 2400 of FIG. 24. In this case, the sampling point 2410.2located within the room will draw a sample air indicating the presenceof smoke particles in plume 2413. Once an initial detection is made thedetector 2411 will then perform localization as described above and sendan alert signal to the fire alarm control panel (FACP) indicating theposition of the suspected fire. As is conventional in such systems theoutput signal of the detector 2411 can indicate a level of particlesdetected or an alarm state determined according to alarm logic of thedetector. The fire alarm control panel will communicate this alert datavia central controller 2412 back to the central monitoring station 2414where staff can monitor conditions in the building 240. Because thesystem includes video verification capabilities, upon detection ofparticles in zone 2 via inlet 2410.2, video verification using camera2402 is activated. The camera 2402 begins either capturing (if it wasnot previously capturing images) images or analysing images to determinewhether smoke can be verified to be present from the images. The videofeed from the camera 2402 is provided to the central controller 2412.The central controller 2412 performs video analytics on a series offrames captured by camera 2402 to determine if there are visual featuresin the images which indicate either the presence of smoke or flamewithin the field of view 2402.1 of the camera 2402. This video analyticscan be performed either in the controller 2412 or at the centralmonitoring station 2414. If the analysis is to be performed at thecentral monitoring station 2414 the video images, perhaps in acompressed form, will need to be transmitted from the site controller2412 to the central monitoring station 2414 for analysis. Upon detectionof smoke or fire in the images captured by camera 2402 the alert systemrunning at the central monitoring station 2414, can modify its output toindicate that the alert condition indicated by the smoke detector 2410.2is verified by the video analytics system. From this verification a usercan infer that the chance of a false alarm is low.

By indicating to the user monitoring the central monitoring station 2414that a fire or smoke alarm has been verified, the importance level ofthat alarm will be raised. Accordingly the person monitoring the systemwill be encouraged to act more quickly on the alert. FIGS. 25 and 26show two alternative interfaces which can be provided for the centralmonitoring station according to embodiments of the present invention.Turning firstly to FIG. 25, the interface includes a plurality of videodisplay panes 2501, 2502, 2503 and 2504 each of which displays imagescaptured from different cameras within the building 2400 which is beingmonitored. The large viewing pane 2501 is provided in order to give acloser view of a location to the user of the monitoring system such thatthey can visually inspect a scene at which an alert has occurred. Thesmaller display panes 2502 through 2504 may cycle according to anappropriate scheme or alternatively be ranked in a priority orderaccording to alert levels in the corresponding zones. The bottom portionof the interface 2500 includes a list of events 2507. For each event,event data is displayed and the user of the system is provided with aseries 2509 of buttons for performing certain response actions. For eachevent the following data is displayed: an event number 2512 being anumerical listing of events, an “Event ID 2514 being a system-wideunique identifier for the event used for indexing logged event data foraccess at a later time; an event description 2516 explaining the natureof the event; an event level 2518 being a priority ranking for theevent; an indicator of the status 2520 of the event e.g. whether it isan alarm or fault or other particular type of alert a series of actionbuttons 2522.1, 2522.2, 2522.3.

Event number 5 in the present example, has the highest alert status andwill be described herein in more detail. Event number 5 is an indicationthat smoke has been detected in zone 2. The smoke in this example hasbeen detected by particle detector 2410.2 at a level indicating thatalarm should be raised. In the status column, the event is indicated as“alarm verified” because the video analytic system has analysed theoutput of camera 2402 and determined that smoke and fire is present. Inorder to indicate the verification to the user of the system, theinterface has highlighted the status box corresponding to event number 5and indicated in text form that the alarm is “verified”. As willadditionally be noted the image of zone 2 includes a visual indicator2508 of the location of the smoke and fire detected by video analyticssystem. In this regard, the video analytic system has performed ananalysis of a series of images captured by camera 2402 and has indicateda boundary or edge around a region within the image which is determinedto represent smoke. Additionally, an indication of a zone within theimage 2510 is indicated as appearing to represent flame which is causingthe fire.

FIG. 26 shows an alternative interface to that of FIG. 25 the onlydifference between the interfaces of the two figures is that rather thansimply indicating that the status of event number 5 has been “verified”the interface of FIG. 26 orders each of the events in the event listaccording to their alarm level and verification level. This additionallyhighlights that greater priority should be given to event number 5compared to the other events within the system.

Once an event has been detected and verified by the automatic videoverification system it will be up to a human user of the system todetermine an action to be performed in response to the event. The personmay choose to dismiss the event (2522.2) or view the video feed (button2522.1) corresponding to the event to further investigate or to raise anexternal alarm (2522.3) by either calling Police, fire brigade or otherappropriate emergency response services. This can be performed using theinterfaces of FIGS. 25 and 26 using the buttons view (2522.1), dismiss(2522.2) or call (2522.3) as indicated.

In an additional embodiment of the present invention, it is advantageousthat the video analytic system further assists the user in theirinvestigation of pending events. In this regard, a user of the systemmay wish to investigate the cause of an alert, for example bydetermining where the event has originated, or what the true cause of anevent is, for example what or thing is on fire or in danger of being setalight and is causing a smoke detection event. Such information can beparticularly valuable in determining a response strategy to an alertcondition. For example, if it is known exactly what is on fire anappropriate suppression strategy can be implemented. Moreover, anythingsurrounding the fire can be visually inspected to determine what levelof response is needed. For example, if important equipment or hazardousor flammable items surround the area above the fire is, a fasterresponse may be needed or total evacuation whereas if a fire is detectedin a relatively open area or area in which non-flammable items arelocated a slower (or at least different) response may be acceptable.

In order to assist in the investigation process, the central monitoringstation can be provided with software which analyses alarm outputs fromone or more cameras and condition sensors and makes a recommendation toa user as to the order of recommended investigation as to the source ornature of the event. For example, the software system can store a map orother geographical data as to the relative position of rooms and itemsin the premises being monitored, and using data representing whichsampling inlets have received particles, determine either a likelycentral point at which the fire has originated or an investigationpriority. For example, in FIGS. 25 and 26 a verified alarm has beensensed in zone 2 and an unverified alarm has been sensed in zone 3. Apre-alarm has also been sensed in zone 1. In a situation in whichverification of the presence of flame (indicated at 2510 in FIG. 25) isnot possible, the central monitoring station will recommend an order ofmanual analysis of other zones in order of zone 2, then zone 3, followedby zone 1, followed by zone N. This is based on received alert levels ofzones 2, 3 and 1 and the proximity of the doorways of zones 2, 3, N and7, and the fact that zone 1 is a corridor between them. In otherembodiments other factors can also play a role in determininginvestigation order, e.g. if the building's air conditioning return ductis located at position 2420 abnormal particle levels detector via points2410.12 may be treated as lower priority other air sampling points as itwill tend to indicate smoke more often than other air sampling points.

Thus should smoke be detected at in e.g. zone 2 and zone 1 at samplingpoint 2410.12 then zone 2 is likely to be the source of the fire.Conversely if only sampling points 2410.11 and 2410.12 are determined tohave drawn a sample containing smoke, but no other sampling points, thenzone 1 is the likely source of the fire condition.

It is also useful to note that without the video verification processapplied to event 5 in FIGS. 25 the alarm level of zones 2 and 3 would beotherwise identical. Without video verification there will be noadditional information on which to base a decision that the fire isactually present in zone 2 and not zone 3 other than physicalinspection. This clearly aids with the response strategy which becauseof the video verification process described herein enables a response tobe targeted on zone 2 first which is where the fire is actually present.

The sensors (e.g. cameras) described in the illustrated may be fixedcameras or be capable of changing their field of view, e.g. bepan-tilt-zoom (PTZ) cameras. If a PTZ camera is used the camera can beprogrammed to pan, tilt, and zoom either to isolate locations that areidentified as potentially causing an alert condition to enableinvestigation, Alternatively or additionally the PTZ camera can becontrolled such that is captures images of a first view, and then movesto a second view and possibly one or more additional views successively,pausing for a specified time at each view. The sequence can be repeatedindefinitely.

Video analysis can be performed on each view independently of the otherviews. In general terms this can be considered a process of performingtime division multiplexing of images taken with the one camera atdifferent PTZ settings, with each PTZ setting corresponding to a timeslot. The video analytics can be performed on a series of images fromsuccessive instances of each PTZ time slot. Images captured incorresponding PTZ time slots can be treated as a “camera” and videoanalytics can be performed using the techniques described in earlierexamples for a single camera.

Systems such as this add an extra dimension to thecommissioning/calibration process described above, in that it isnecessary to correlate the location of the air sampling inlets withtheir physical locations and also with the views of the cameras of thesecurity system. In some cases it might even be desirable to correlatePTZ parameters of a particular cameras with a sampling point.

An apparatus and method for correlating an address in a particledetection system, said address corresponding to a physical location,with a location being monitored in a video capture system that monitorsa plurality of locations will now be described in connection with FIG.27. FIG. 27 illustrates an exemplary apparatus 2700 that can be used forconveniently commissioning, calibrating and/or testing particledetection systems. It could also be used in non-video enabled particledetection systems such as conventional Aspirating particle detectionssystems, as will be apparent from the following description.

The apparatus is arranged to provide a mechanism to perform smoke testssuch that the location of the smoke can be learned by the smoke detectorsystem and in the case of a system with video verification of alerts,the security system also in a simultaneous fashion. The apparatusenables the operator to inject smoke (or other test particle) at eachsampling inlet of an air sampling particle detection system, pointdetector or other smoke sensing device, preferably in no particularsequence, and record e.g. on an integral computer device such as tabletcomputer or the like, the physical location of the inlet or sensingdevice. The data can be transferred to the particle detector either inreal time or afterwards, so that the particle detector knows which inletis mapped to which physical location. Preferably (but not essentially)the apparatus enables the security system to identify which particularcamera (and optionally PTZ parameters) is associated with each inlet'saddress location. Association of the inlet or sensor location with alocation in the video security may be achieved by visible means. As thesmoke injection occurs, the visual indicator is activated, e.g. byflashing a code for a time. The security system searches for the visualindicator and identifies images of it amongst the images captured by itsvarious cameras. The security system can then correlate the right cameraand optionally PTZ position with location of the air sampling inlet orsensor. Thus the apparatus 2700 according to the preferred embodimentincludes:

-   -   a mechanism for delivering (and preferably generating) smoke to        the a sampling inlet;    -   means for enabling detection of the apparatus in an image        captured by the video security system, and optionally means to        communicate data over this optical means.    -   means for synchronising the actions of the apparatus with the        particle detection system and/or security system.

More particularly the exemplary device 2700 includes:

-   -   A controller 2702 that controls operation of the device        apparatus 2700.    -   A power supply 2704, which will typically be a battery.    -   A smoke generator 2706 to produce test smoke for introduction to        the sampling points as needed.    -   A fan 2710 to push the smoke to the point of delivery.    -   A duct 2712 to guide the smoke generated by the smoke generator        2706 to the point of delivery. In this example the duct 2712 is        an extendible, e.g. telescopic, pipe to enable convenient use        with sampling points at different heights and convenient device        storage. The duct 2712 terminates in an exit port 2714 that is        shaped to enable easy coupling to or around a sampling point. In        this example the exit port 2714 is a funnel shaped exit port,        that can fit over or around a sampling point.    -   A user interface 2716, which in this case includes one or more        control buttons 2718 and a touch screen display 2720. These can        be configured, in a manner know to those skilled in the art to        control operation of the apparatus 2700 and enter data as will        be described below.    -   A synchronisation port 2722, which can be a wired or wireless        communications means for establishing data communications with        external devices, e.g. the smoke detection system, video        security system or elements of these systems. In the case that        the port 2722 is wireless, the port 2722 can be used for        real-time communications. If the port 2722 is adapted for making        a physical connection, communications could be made in real time        (e.g. my being plugged into the other systems during use) or        asynchronously (e.g. sharing stored data and/or synchronisation        of the device with one or both of the smoke detection system and        video security systems after use).    -   A visual communications system 2724, which in this case includes        an arrangement of radiation emitters 2724.1, 2724.2, 2724.3. The        visual communications system can be used to communicate with the        security system during use of the apparatus 2700, in a manner        described below. The visual communications system 2724 may emit        visible or invisible radiation, so long as it can be received        and relayed to the video surveillance system. Most preferably        the radiation is received by the security system and captured in        its video images of a region. In this way, the presence of the        apparatus 2700 and (optionally data) is conveyed by the state of        the visual communications system 2724.

An exemplary use of the test apparatus 2700 will now be described inconnection with commissioning a particle detection system that has avideo verification performed by a video security system. The objectiveof the apparatus 2700 is to assist and preferably automate theconfiguration and verification of the integration between smokedetection system and video security system. Specifically, the tool aidsthe smoke detection system and video security system to have the samesense of physical locations that is being protected.

Prior to the start of the training process, the particle detector systemand video security system is set to a “training” mode.

At each sampling inlet of the particle detector system smoke isgenerated by the technician using the apparatus 2700. When triggered,the apparatus 2700 generates an amount of smoke sufficient to triggerthe particle detection system to detect particles. The trigger togenerate smoke will also switch on a visual indicator that isdistinguishable from background entities in the images captured by thesecurity system. While in the “training” mode the video security systemanalyses the imaged captured by it, and searches (either periodically orcontinuously) for the visual indicator 2724 in the images. Once found,it will record the apparatus's location (camera and PTZ presets ifnecessary) to identify which video camera will have the area surroundingthe sampling hole in its field of view.

At the point of generating the smoke, the technician also records a name(and optionally a description) of the physical space e.g. using akeyboard interface on the touch screen display 2720. This text is storedalong with the smoke test start and end time, and is optionallytransmitted to the smoke detector and/or security system for correlatingwith detected events in these systems. During normal operation the textentered at this point can be presented to the CMS operator when thesampling hole is identified during actual use of the system.

The apparatus 2700 is configured e.g. programmed to guide the technicianas to what action to take next, e.g. when move to a new sampling point,whether the technician needs to wait before triggering the smoke, theperiod that the technician needs to dwell with the smoke generator atthe current hole, prompt for technician for name of the sampling holeetc.

Sampling points are typically located near the ceiling though there willbe exceptions. The generated smoke needs to reach the sampling holequickly and directly. However, it is strongly desirable that thetechnician always remain on the ground even when they trigger smoke tobe presented in close proximity to a sample hole mounted high up in theceiling, thus all controls are located at the bottom of duct 2712, andthe duct 2712 is extensible.

The smoke generation start and end events for each sampling hole issynchronised with the particle detection system and video securitysystem. This synchronisation can be done in real time over a wirelessnetwork. Optionally or alternatively the apparatus 2700 can provide thesame capability without the real time use of wireless networks in anoffline mode. For this later case, at the completion of thecommissioning process the apparatus 2700 will need to be connected withthe particle detection system and video security system to synchronisethe recorded data including the name of the physical spaces. This couldbe performed via any communications medium or channel, including but notlimited to, USB, Ethernet or WiFi.

In the example of FIG. 24 the following series of data are generated inthe “training” mode by the test apparatus, smoke detection system andsecurity system respectively.

TABLE 1 Test Apparatus data table Co-ordinate Start time End timePhysical location name (optional) 1:00 1:01 Main Corridor −37.813621144.961389 1:05 1:06 Boardroom −37.813637 144.961398 1:08 1.09 Library−37.813624 144.961398 . . . . . . . . . . . . 1:30 1:31 Cleaner'sCupboard −37.813610 144.961372

TABLE 2 Smoke Detector table Start End Location parameter Inlet number1:00 1:01 130 Liters 5 1:05 1:06 125 Liters 4 1:08 1.09 100 Liters 2 . .. . . . . . . . . . 1:30 1:31  16 Liters 1

TABLE 3 Security System table Start End Camera PT2 1:00 1:01 2401 P = 5T = 20 Z = 200 mm 1:05 1:06 2403 — 1:08 1.09 3402 — . . . . . . . . . .. . 1:30 1:31 2405 —

Once the training data has been recorded by the test apparatus 2700,smoke detector system and security system, this data needs to becorrelated in order for the video verification system and smokedetection systems to work together in the event of an actual smokedetection event. As can be seen the start and end times in each tablecan be used to correlate smoke test data with the smoke detector dataand security system data.

In use, in the event that smoke is detected by the smoke detectionsystem it will determine where in its system smoke was detected. If thesystem includes one or more point detectors “addressing” i.e.determining where the event was detected is relatively straightforwardand only requires knowledge of which detector has detected smoke. If thesystem includes or is an aspirated particle detection system with an airsampling network the system can performs one of the localisation methodsin any one of the following Australian patent applications 2012904516,2012904854 or 2013200353 filed by the applicant or other localisationtechnique to identify the location of the source of the particles. Theoutput could be a location, name (e.g. the name given by the technicianduring commissioning) room address or a smoke localization parameter(such as a volume of air sample that has passed through the detectorbetween detection events whilst in the localisation phase, whichidentifies which of the sampling holes the smoke entered the smokedetection system through, using any of the methods described herein.This output is passed to the security system. On the basis of this name,identifier or localization parameter the security system is able todetermine which of its cameras provide a view of the determined airsampling point.

In this case, the security system will identify camera 2405 as thecamera which will show a view of the region in which the smoke detectionevent has taken place.

As will be appreciated, additional information could be gathered duringcommissioning to aid the CMS operator in determining an appropriateaction when smoke or a fire is detected.

Additional features can also be included in some embodiments of theapparatus 2700. For example, in some embodiments other methods can beused to determine the location of the apparatus 2700 to assist orautomate identification of the location and sampling inlet. For examplesatellite positioning (e.g. GPS or DGPS) or triangulation fromelectromagnetic emitters, could be used to determine which room theapparatus is in, thereby obviating or minimising the need to enter datainto the system. The sampling point may be provided with a short rangecommunications mechanism, e.g. an RFID tag, that is read by a readermounted near the end of the duct 2712 to identify which sampling pointis being commissioned in each step. This communication could also beused as the trigger for beginning the test procedure for the samplingpoint.

FIG. 17 illustrates a variant of the system of FIGS. 14A to 14E. Thesystem 1700 is identical in all respects to the system of FIGS. 14A to14E and operates in the same manner, with the exception that the sampleamplification arrangement 1702 is located at the upstream end of thesampling pipe 28. This simplifies the detector end of the samplingnetwork 26 and facilitates retrofitting of a sample amplificationarrangement 1702 to a legacy detection system that was originallyinstalled without such a capability.

FIG. 18 illustrates a particle detection system including an airsampling network that has a sample amplification arrangement comprisinga plurality vibrating membranes. Essentially this system 1800 is adouble ended version of the systems of FIG. 14A to 14E and FIG. 17. Inthis embodiment the two pistons 1802, 1804 (formed from the vibratingmembranes of loudspeakers) act together to form the sample amplificationarrangement. These can be operated in concert as described in connectionwith opposing fans of FIG. 15. However, being loudspeakers (or othersimilar air movement device capable of causing rapidly oscillating airflow) these pistons 1802, 1804 offer new the ability to selectivelyperform sample amplification at one or more sample inlets 29 along thesampling pipe 28. This can be achieved by oscillating the pistons with aselected phase difference between them. This causes selectivereinforcement or cancellation of the sample amplification action atdifferent places along the sampling pipe 28.

FIG. 19 illustrates another particle detection system including an airsampling network with branched sampling pipes and which has a sampleamplification arrangement comprising a plurality vibrating membranes.The system 1900 includes a particle detector 11, coupled to an airsampling system 26. The air sampling system 26 is branched such that ithas sampling pipes28A and 28B each of which includes a plurality ofsample inlets 29A and 29B arranged in series along their length. At theupstream ends of the pipes 28A and 28B are located pistons 1902, 1904. Acommon piston 1906 is placed at the downstream end of the samplingnetwork 26. The sample amplification arrangement comprising the pistons1902, 1904, 1906 can be operated to selectively cancel its oscillationeffect by choosing appropriate phase differences between oscillation ofthe pistons in the sample amplification phase. For example in theexample the downstream piston 1906 is operated in phase with theupstream piston 1902 on the pipe 28A, but out in anti-phase to theupstream piston 1904 on the pipe 28B. The result is that sampleamplification occurs only on the sample inlets 29A but not on inlets29B.

This process can be extended and combined with the method described inconnection with FIG. 18. In this regard, greater selectivity can beachieved by operating the downstream piston 1906 is with a selectedphase difference to the with the upstream piston 1902 on the pipe 28A,and no oscillation of piston 1904. Most preferably, if a node in theoscillation pattern coincides with the junction between the pipes 28Aand 28B sample amplification will be minimised (or possibly eliminated)on pipe 28B and selective sample amplification can be achieved along thelength of pipe 28A.

As will be appreciated the double-ended sample oscillation techniquesdescribed in connection with FIGS. 18 and 19 could also be implementedwith other types of air flow movement devices, e.g. bellows, fans (asillustrated in FIG. 15) or the like.

The systems of FIGS. 17 to 19 could be implemented such that thelocalisation hardware is provided in a detector-end module, such asmodule 2004, described above. As will be appreciated this maynecessitate the use of a return pipe segment to enable location of theupstream components (e.g. pistons 1702, 1804, 1902) physically near tothe downstream end of the pipe 28 so that they can be housed together inthe module.

Although a purge step is only described in connection with the exampleof FIG. 15B, it should be appreciated that a purge phase may optionallybe used in all embodiments described herein to improve accuracy oflocalisation. A purge step, generally speaking involves filling the airsampling network with clean air (or at least air that is distinguishablefrom sample air), which will typically necessitate means for providingsaid air, e.g. a filter arrangement that is selectively insertable intothe system to enable delivery of clean air. Therefore, where applicablesuch means can be provided in the systems described herein.

As will be appreciated from the foregoing, a number of techniques havebeen described within this document to improve addressing in aspiratedparticle detection systems which include centralised detector and aplurality of sample inlets placed along a duct or pipe of an airsampling system. It will be apparent to those skilled in the art thatelements of each of the systems could be combined to further enhancesystem performance. To give but one example, the pipe network worksystem of FIGS. 14, 15 or 16 could be used to increase smokeconcentrations within the pipe network to deliver a clearer smokeconcentration front to the detector for use in the cross-correlationmethod described in connection with FIGS. 5 and 6. Moreover, instead ofusing time based correlation, volume based correlation could be used asdescribed above. Other combinations will be readily apparent to thoseskilled in the art.

It will be appreciated that the present invention, although described inrelation to the detection of smoke, can equally be applied to any othermaterial that can be usefully detected by a sampling system, includinggases, dust, vapour, or biological materials.

FIG. 30 illustrates a further embodiment of a localisation module 3000that can be used as a localisation module 2004 in any one of theembodiments illustrated herein. The localisation module 3000 containsthe following main elements:

A main flow path 3002 that extends from the sampling pipe 28 at one end(the inlet 3004 to the localisation module 3000) to the detector 11 atthe other end (the outlet 3006 from the localisation module 3000). Themain flow path 3002 includes an additional particle detector 3010. Theparticle detector 3010 may be a particle detection chamber that iseither the same or different to the main particle detection chamber 14,or of a different type. In a preferred form the secondary particledetector provides a faster response to particles than the main detectionchamber 14, although this is not necessary in all embodiments. The mainflow path 3002 also includes a valve (3012) that can be used to closeoff the main flow path 3002 and divert all flow into a primary branchflow path 3014, described below in more detail.

The primary branch flow path 3014 includes a first branch 3016 leadingto a sample amplification device 3018. In a preferred form the sampleamplification device 3018 takes the form of a reciprocating piston thatcan be used to rapidly switch between pushing and pulling a small amountof air within the sampling pipe. The primary branch flow path 3014includes a second valve (3020) that can be used to block access to thepiston and divert flow from the primary branch flow path 3014 into asecondary branch flow path (3022).

The secondary branch flow path 3022 contains a fan 3024 and a filter3026 that are arranged to enable air to be drawn into the secondarybranch flow path 3022 from outside the system, filter the air, and passit to the additional particle detector 3010 in a manner described below.

FIG. 31 illustrates a localisation module 2004 that has been extended tooperate with an air sampling network 26 having multiple air samplingpipes 28.2, 28.2. The localisation module 2004 could be extended tohandle multiple sampling pipes by duplicating the components describedabove. However, in order to reduce parts count and/or cost of goodscertain components may be shared. In this embodiment independent mainflow paths 3002.1 and 3002.2 are provided. In this case the valves(3012.1 and 3012.2) are operated together and connected to respectivebranches of the primary branch flow path and operated in concert witheach other. In most multi-pipe systems e.g. Vesda Laser Scanner or VesdaLaser industrial (both sold by Xtralis Pty Ltd) the main particledetector still only has one detection chamber and the air samples fromeach of the pipes are mixed together in a manifold prior to analysis inthe detection chamber.

In all other respects the multipipe localisation module is the same asthat of FIG. 30 and matching reference numerals have been used. As willbe appreciated a multipipe localisation module can be made to handle anynumber of sampling pipes required.

FIGS. 32 and 33 illustrate two additional embodiments of the accessory2800. The accessories 2800 may be used as pipe end-caps that are mountedat the far upstream end of a sampling pipe 28. However, they may also beplaced at other points in the sampling network e.g. at the upstream endof a branch pipe or off a T junction at an intermediate point in asampling pipe, such that selective opening of the accessory flow pathallows air into the sampling pipe. The embodiment of FIG. 32 has a fan3202 and a valve 3204 (equivalent of valve 2808 of FIG. 28) that can beactivated under control of the localisation module. In normal smokedetection operation the valve 3204 is closed and the fan 3202 does notrun. When activated, the valve 3204 is opened and the fan 3202 isactivated so that air is drawn into the end of the pipe 28 and blowndown the sampling pipe towards the detector 11. The accessory 2800 canalso optionally include a filter, such as a HEPA filter so that the airentering the pipe is better able to be distinguished from sample airdrawn into the system from sampling points.

The accessory 2800 of FIG. 33 is very similar to the embodiment of FIG.28 and like features have been like numbered. The accessory includes avalve 2808 that can selectively open the pipe, but no fan. It alsoincludes a filter 3302. The valve 2808 is actuated by the controller2806 upon sensing low pressure or back-flow in the sampling pipe 28.When a high negative pressure is detected, the end cap is opened toallow air to be drawn into the end of the pipe.

In use in a preferred embodiment the particle detection system using alocalisation module of the type illustrated in either of FIGS. 30 and 31and an accessory illustrated in either of FIG. 32 or 33 will have thesame general architecture as that show in other embodiments such as FIG.29, with a main particle detector, localisation module 2004, samplingnetwork 26 with sampling pipes 28 and at least one accessory mountedupstream of the localisation module. Operation of such a system will nowbe described assuming use of the accessory of FIG. 32.

In overview, the detector 11 operates in a normal particle mode drawingair samples and analysing them continuously. However once particles aredetected above a trace level the system does into a localisation modeand activates the localisation module 2004. The main detector 11 is thende-activated and air samples cease to be drawn through the main detector11. The localisation module 2004 then performs a sample amplificationroutine as described above. As noted above “amplification” mixes the airin the pipe with the local atmosphere surrounding each sample hole andcauses packets of air in the sampling pipe adjacent each sampling holeto form—these packets have a composition similar to the atmosphereimmediately surrounding the sampling point. As will be apparent from theforegoing description, in normal steady state operation the air sampledrawn in through each sampling hole is diluted by the air drawn into allother sampling holes as it passes through the sampling network 26.However, in this embodiment, because the amplification only sucks andblows a small amount of air back and forth through the system thepackets are not diluted in this way.

The contents of the sampling pipe with “packets” is then drawn back tothe additional particle detector 3010 for analysis by re-activating themain fan of the main detector and, if an accessory with a fan is used(e.g. that of FIG. 32) by pushing it with the accessory's fan. Duringthis “transportation” process the volume (or a related value) ismeasured. When the additional particle detector 3010 detects a packet ofsmoke, the drawn volume is read off and compared to a look-up table todetermine which sampling hole corresponds to the smoke packet that wasdetected.

The secondary branch flow path does not play any part in thislocalisation process. However, it is only used to flood the additionalparticle detector 3010 with clean air for calibration. This processhappens periodically, say once a day.

In tabular form the process can be viewed as follows:

Normal Operation

Volume Additional or End cap Main particle Fan in volume- fan MainDetection Flow Valve Valve Sample detector branch related Valve 3202 (ifaspirator chamber sensor 3012 3020 Amplifier 3010 3024 measure) 3204present) On On Active Open Closed Inactive Inactive Off Inactive closedOff

-   -   Where for Valve 3012        -   Open=main flow path open and primary branch flow path            blocked        -   Closed=main flow path blocked and primary branch flow path            open for Valve 3020        -   Open=primary branch flow path open so sampling pipe open to            amplifier        -   Closed=secondary branch flow path open so sampling pipe open            to fan and filter

If trace level smoke detected by the main detection chamber then normaldetection is ceased and an amplification mode is entered.

Amplification

In this state the localisation module 2004 enters its amplification modeand in this example the sample amplification device, e.g. piston 3018,repeatedly draws and pushes air to perform sample amplification. Thevolume of air moved in this process is low compared to the total volumeof air in the air sampling system and is preferably less than half thevolume of the sampling pipe between neighbouring sampling inlets.

Volume Additional or End cap Main Sample particle Fan in volume- fanMain Detection Flow Valve Valve Amplifier detector branch related Valve3202 (if aspirator chamber sensor 3012 3020 3018 3010 3024 measure) 3204present) Off Off inactive closed Closed Oscillating Inactive OffInactive Closed Off

After some predetermined time or number of oscillations, amplificationis ceased and the system moves into Transportation mode.

Transportation

In this mode the system moves the amplified sample packets back to theadditional particle detector 3010 for analysis. The volume of sample airthat has passed through the system since transportation started, or avolume related value is measured, e.g. by integrating flow rate. Thisvalue is correlated with detection events in the additional particledetector 3010 to determine entry point of smoke.

As noted elsewhere herein transportation is preferably done at highspeed. This is aided by opening a large port into the sampling pipe e.g.by opening valve 3204 (and if present) activating the pusher fan 3202.Opening the pipe's 28 end and blowing into the pipe's end causes apositive pressure in at least part of the pipe (the portion closest tothe fan 3202) and minimises negative pressure (reduces suction) closerto the main aspirator of the system. This minimises the suction at thesampling inlets of the sampling pipe and consequently minimises thedrawing of additional air into the sampling inlets duringtransportation, thus minimising dilution of the sample packets as theyare sent to the particle detector for analysis.

Drawback is also preferably done at high enough speed to ensureturbulent flow in the sampling pipe, which minimises smearing out ofpackets along the pipe (as described elsewhere herein). .A furtheradvantage of high speed drawback during transportation is that itreduces transport time of packets from the far end of the sampling pipe28 to the detector(s) enabling quicker response

Volume Additional or End cap Main Sample particle Fan in volume- fan3202 Main Detection Flow Valve Valve Amplifier detector branch relatedValve (if aspirator chamber sensor 3012 3020 3018 3010 3024 measure)3204 present) On Off or on Active open Closed inactive Active Off Activeopen On

After drawback is complete, the system goes back into normal operation.

The process can be cycled so as to update localisation dataperiodically, and also monitor smoke development.

Use of the Secondary Branch Flow Path 3022

As will be appreciated from the above description the secondary branchflow path 3022 plays no role in normal detection, amplification ortransportation phase. The main use of the secondary branch flow path isto provide a source of clean air that can be used to calibrate or zeroeither one or both the main detection chamber 14 or additional particledetector 3010 either periodically or when needed. This is performed bygoing into a zeroing mode in which filtered air is blown back throughthe secondary branch flow path into the main flow path until at leastthe additional particle detector 3010 is full of clean, filtered air. Inthe zeroing phase the system configuration is as follows:

Volume Additional or End cap Main Sample particle Fan in volume- fanMain Detection Flow Valve Valve Amplifier detector branch related Valve3202 (if aspirator chamber sensor 3012 3020 3018 3010 3024 measure) 3204present) Off Off Inactive Closed open inactive Active On inactive closedOff

It is only necessary to blow enough clean air into the localisationmodule 2004 to fill the additional particle detector 3010. This can bedone, for example, by running the fan 3024 for some pre-set time that issufficient to blow as acceptable volume of clean air into the system.Alternatively clean air could be blown back into the additional particledetector 3010 until a relatively steady minimum particle reading isdetected by the additional particle detector 3010.

In a further embodiment there is provided a method in a particledetection system having a particle detector in fluid communication withan air sampling network including at least one air sampling pipe and aplurality of air sampling points. The method generally involves, fillingat least one air sampling pipe which has a plurality of air samplinginlets with a calibration substance (e.g. test smoke, or other substancedetectable by the particle detector such as FM200 or the like) that isable to be detected by the particle detection system, said air samplingpipe being filled with said substance at a level detectable by theparticle detection system. Next the method involves drawing an airsample into the sampling pipe to cause localised dilution of thesubstance around at least one air sampling inlet. Preferably thedilution process involves changing flow direction in the sampling pipe.Most preferably the dilution process is similar to sample amplificationas described elsewhere herein. The contents of the sampling system arethen moved to the detector whilst detecting the level of calibrationsubstance in the contents of the air sampling system, whilst alsomonitoring a quantity that can be correlated with the movement of thecontents of the sampling system (e.g. volume, a volume related value, ortime (although this is not preferred). Detecting said localised dilutionin the substance in the contents of the sampling pipe and correlatingsaid detection with the monitored quantity, to determine a value of saidquantity corresponding to a sampling hole that caused the localiseddilution. Detecting said localised dilution in the substance in thecontents of the sampling pipe comprises detecting a reduction inparticle level by a particle detector of the system.

The present method can form part of a commissioning process and inessence is the converse of the typical localisation technique, insofaras instead of amplifying a sample to create packets of sample, thesubstance-laden (e.g. smoke filled) sampling pipe has diluted packetscreated within it by the “amplification” process. Since the whole pipecan be flooded with the calibration substance simultaneously andmultiple, and physically separated dilution packets createdsimultaneously, calibration can be performed of a greater number ofsampling holes at the same time.

In order to implement such a system a method, filling of the samplingpipe can be manual via a sampling inlet or more preferably the samplingnetwork can be fitted with an inlet such as a spigot (e.g. as part ofthe accessory 2800 or localisation module 2004). The latter is probablymore convenient since in multi-pipe embodiments all pipes can becalibrated at once. The inlet is in fluid communication with a supply ofcalibration substance that has an approximately regulated output. Thesource of calibration substance can be connected to the inlettemporarily during calibration or permanently and enable periodiccalibration and self test.

It will be understood that the invention disclosed and defined in thisspecification extends to all alternative combinations of two or more ofthe individual features mentioned or evident from the text or drawings.All of these different combinations constitute various alternativeaspects of the invention.

The invention claimed is:
 1. A smoke detection system having at leastone particle detector, a main aspirator and an air sampling systemhaving at least one sampling pipe with a plurality of sampling inletsthrough which smoke can enter the air sampling system, the smokedetection system being configured to: operate in a detection mode inwhich the main aspirator draws air samples through the sampling inletsalong the sampling pipe to at least one particle detector for analysis;and to operate in a localisation mode in which a smoke detector of thesmoke detection system operates with a second smoke detection responsewhich is faster than a smoke detection response in the detection mode,to determine which of the plurality of sampling inlets smoke has enteredthe air sampling system.
 2. The smoke detection system as claimed inclaim 1 in which the smoke detection system is configured to enter thelocalisation mode after smoke is detected in the detection mode.
 3. Thesmoke detection system as claimed in claim 2 which is further configuredto operate in a purge mode in which the air sampling system is flushedof sample air after smoke is detected in the detection mode.
 4. Thesmoke detection system as claimed in claim 3 in which the smokedetection system is configured to enter the purge mode after smoke isdetected in the detection mode, before entry into the localisation mode.5. The smoke detection system as claimed in claim 1 which includes onesmoke detection chamber arranged to operate with at least one differentoperational parameter in the localisation mode and the detection mode.6. The smoke detection system as claimed in claim 1 which includes aplurality of smoke detection chambers, including a first smoke detectionchamber arranged to operate with said smoke detection response in thesmoke detection mode, and a second smoke detection chamber arranged tooperate with said second smoke detection response in the localisationmode.
 7. The smoke detection system as claimed in claim 6 wherein whenin the localisation mode the first smoke detection chamber outputsparticle concentration for the particle detection system, and an outputof the second smoke detection is used to determine which of theplurality of sampling inlets smoke has entered the air sampling system.8. The smoke detection system as claims in either of claim 6 or 7 inwhich the first and second particle detection chambers are arranged inseries.
 9. The smoke detection system of any one of claims 6 to 8wherein the first and second smoke detection chambers are part of thesame particle detector.
 10. The smoke detection system as claims inclaim 5 wherein the smoke detection chamber is arranged to operate witha reduced period over which particle concentration levels are averagedto produce a second smoke detection response.
 11. A method of smokedetection in a smoke detection system having at least one particledetector, a main aspirator and an air sampling system having at leastone sampling pipe with a plurality of sampling inlets through whichsmoke can enter the air sampling system, the smoke detection methodincluding: operating a particle detector in a detection mode comprising:drawing an air sample through the sampling inlets along the samplingpipe with the main aspirator to at least one particle detector;analysing the air sample to determine particle concentration; andentering a localisation mode; operating a particle detector in thelocalisation mode comprising: operating a particle detector of the smokedetection system with a second smoke detection response which is fasterthan a smoke detection response in the detection mode, determining whichof the plurality of sampling inlets smoke has entered the air samplingsystem on the basis of an output of the particle detector operating withthe second smoke detection response.
 12. The method of claim 11 whereinthe method includes entering the localisation mode after smoke isdetected in the detection mode.
 13. The method of claim 12 which furtherincludes: operating in a purge mode in which the air sampling system isflushed of sample air.
 14. The method of claim 13 wherein the smokedetection system operates in purge mode after smoke is detected in thedetection mode, and before entry into the localisation mode.
 15. Themethod of claim 11 wherein the method includes: operating at a smokedetection chamber arranged with at least one different operationalparameter in the localisation mode and the detection mode.
 16. Themethod of claim 11 wherein the smoke detection system includes aplurality of smoke detection chambers, including a first smoke detectionchamber arranged to operate with said smoke detection response in thesmoke detection mode, and a second smoke detection chamber arranged tooperate with said second smoke detection response in the localisationmode; and the method includes directing sample air to the second smokedetection chamber in the localisation mode.
 17. The method of claim 15which includes reducing the period over which particle concentrationlevels are averaged to produce the second smoke detection response.